I think the best approach for this is to combine 

1. [Converting Markdown to HTML][1] &
2. [Displaying HTML in WinForms][2]

The most up to date Markdown Library seems to be [**markdig**][3] which you can install [via nuget][4]

[![Nuget > Markdig][5]][5]

A simple implementation might be to:

1. Add a `SplitContainer` to a `Form` control, set `Dock = Fill`
2. Add a `TextBox`, set `Dock = Fill` and set to `Multiline = True`
3. Add a `WebBrowser`, set `Dock = Fill`

Then handle the `TextChanged` event, parse the text into html and set to `DocumentText` like this:

```cs
private void textBox1_TextChanged(object sender, EventArgs e)
{
    var md = textBox1.Text;
    var html = Markdig.Markdown.ToHtml(md);
    webBrowser1.DocumentText = html;
}
```

Here's a recorded demo:

[![Demo screen share][6]][6]


  [1]: https://stackoverflow.com/q/460483/1366033
  [2]: https://stackoverflow.com/a/12724381/1366033
  [3]: https://github.com/lunet-io/markdig
  [4]: https://www.nuget.org/packages/Markdig/
  [5]: https://i.stack.imgur.com/Gl8UV.png
  [6]: https://i.stack.imgur.com/XcOsX.gif

[We have a Windows Forms database front-end application that, among other things, can be used as a CMS; clients create the structure, fill it, and then use a ASP.NET WebForms-based site to present the results to publicly on the Web. For added flexibility, they are sometimes forced to input actual HTML markup right into a text field, which then ends up as a varchar in the database. This works, but it's far from user-friendly.]

As such… some clients want a WYSIWYG editor for HTML. I'd like to convince them that they'd benefit from using simpler language (namely, Markdown). Ideally, what I'd like to have is a WYSIWYG editor for that. They don't need tables, or anything sophisticated like that.

A cursory search reveals [a .NET Markdown to HTML converter][1], and then we have [a Windows Forms-based text editor that outputs HTML][2], but apparently nothing that brings the two together. As a result, we'd still have our varchars with markup in there, but at least it would be both quite human-readable and still easily parseable.

Would this — a WYSIWYG editor that outputs Markdown, which is then later on parsed into HTML in ASP.NET — be feasible? Any alternative suggestions?


  [1]: http://aspnetresources.com/blog/markdown_announced.aspx
  [2]: http://www.codeproject.com/KB/edit/editor_in_windows_forms.aspx

A WYSIWYG Markdown control for Windows Forms?

I'm a little late to the party, but msdn has a very good answer to this problem [here][1].



    'Ends Edit Mode So CellValueChanged Event Can Fire
    Private Sub EndEditMode(sender As System.Object, e As EventArgs) _
    	Handles DataGridView1.CurrentCellDirtyStateChanged
    	'if current cell of grid is dirty, commits edit
    	If DataGridView1.IsCurrentCellDirty Then
    		DataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit)
    	End If
    End Sub

I also wrote up a very detailed elaboration of the msdn fix and those found here on the post [Firing The DataGridView CellValueChanged Event Immediately][2]


  [1]: http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridview.cellcontentclick.aspx
  [2]: http://codingeverything.blogspot.com/2013/01/firing-datagridview-cellvaluechanged.html

DataGridView.CellContentClick is not firing if I mouse click a DataGridViewCheckBoxCell very fast. How can I solve this? I need to know when CheckBox's check state changes

DataGridView.CellContentClick

You've added a button to your `DataGridView` and you want to run some code when it's clicked.

Easy peasy - just follow these steps:

## Don'ts

First, here's what **NOT** to do:

I would avoid the suggestions in some of the other answers here and even provided by the [documentation at MSDN][DataGridViewButtonColumn] to hardcode the column index or column name in order to determine if a button was clicked.  The click event registers for the entire grid, so somehow you need to determine that a button was clicked, but you should not do so by assuming that your button lives in a particular column name or index... there's an easier way...

Also, be careful which event you want to handle.  Again, the documentation and many examples get this wrong.  Most examples handle the [`CellClick`][CellClick] event which will fire:

> when any part of a cell is clicked.

...but will also fire whenever the *row* header is clicked.  This necessitates adding extra code simply to determine if the `e.RowIndex` value is less than 0

Instead handle the [`CellContentClick`][CellContentClick] which only occurs:

>when the content within a cell is clicked

For whatever reason, the *column* header is also considered 'content' within a cell, so we'll still have to check for that below.

## Dos

So here's what you should do:

First, *cast* the sender to type `DataGridView` to expose it's internal properties at design time.  You can modify the type on the parameter, but that can sometimes make adding or removing handlers tricky.

Next, to see if a button was clicked, just check to make sure that the column raising the event is of type [`DataGridViewButtonColumn`][DataGridViewButtonColumn].  Because we already cast the sender to type `DataGridView`, we can get the `Columns` collection and select the current column using `e.ColumnIndex`.  Then check if that object is of type `DataGridViewButtonColumn`.

Of course, if you need to distinguish between multiple buttons per grid, you can then select based on the column name or index, but that shouldn't be your first check.  Always make sure a button was clicked first and then handle anything else appropriately.  In most cases where you only have a single button per grid, you can jump right off to the races.

## Putting it all together:

### C\#


```cs
private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
    var senderGrid = (DataGridView)sender;

    if (senderGrid.Columns[e.ColumnIndex] is DataGridViewButtonColumn &&
        e.RowIndex >= 0)
    {
        //TODO - Button Clicked - Execute Code Here
    }
}
```

### VB

```vb
Private Sub DataGridView1_CellContentClick(sender As System.Object, e As DataGridViewCellEventArgs) _
                                            Handles DataGridView1.CellContentClick
    Dim senderGrid = DirectCast(sender, DataGridView)

    If TypeOf senderGrid.Columns(e.ColumnIndex) Is DataGridViewButtonColumn AndAlso
        e.RowIndex >= 0 Then
        'TODO - Button Clicked - Execute Code Here
    End If

End Sub
```

---


## Update 1 - Custom Event

If you wanted to have a little bit of fun, you can add your own event to be raised whenever a button is clicked on the DataGrid.  You can't add it to the DataGrid itself, without getting messy with inheritance etc., but you can add a custom event to your form and fire it when appropriate.  It's a little more code, but the upside is that you've separated out what you want to do when a button is clicked with how to determine if a button was clicked.

Just declare an event, raise it when appropriate, and handle it.   It will look like this:

```vb
Event DataGridView1ButtonClick(sender As DataGridView, e As DataGridViewCellEventArgs)

Private Sub DataGridView1_CellContentClick(sender As System.Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick
    Dim senderGrid = DirectCast(sender, DataGridView)
    If TypeOf senderGrid.Columns(e.ColumnIndex) Is DataGridViewButtonColumn AndAlso e.RowIndex >= 0 Then
        RaiseEvent DataGridView1ButtonClick(senderGrid, e)
    End If
End Sub

Private Sub DataGridView1_ButtonClick(sender As DataGridView, e As DataGridViewCellEventArgs) Handles Me.DataGridView1ButtonClick
    'TODO - Button Clicked - Execute Code Here
End Sub
```

---


### Update 2 - Extended Grid

What would be great is if we were working with a grid that just did these things for us.  We could answer the initial question easily: `you've added a button to your DataGridView and you want to run some code when it's clicked`.  Here's an approach that extends the `DataGridView`.  It might not be worth the hassle of having to deliver a custom control with every library, but at least it maximally reuses the code used for determining if a button was clicked.

Just add this to your assembly:


```vb
Public Class DataGridViewExt : Inherits DataGridView

    Event CellButtonClick(sender As DataGridView, e As DataGridViewCellEventArgs)

    Private Sub CellContentClicked(sender As System.Object, e As DataGridViewCellEventArgs) Handles Me.CellContentClick
        If TypeOf Me.Columns(e.ColumnIndex) Is DataGridViewButtonColumn AndAlso e.RowIndex >= 0 Then
            RaiseEvent CellButtonClick(Me, e)
        End If
    End Sub

End Class
```

That's it.  Never touch it again.  Make sure your DataGrid is of type `DataGridViewExt` which should work exactly the same as a DataGridView.  Except it will also raise an extra event that you can handle like this:


```vb
Private Sub DataGridView1_ButtonClick(sender As DataGridView, e As DataGridViewCellEventArgs) _
    Handles DataGridView1.CellButtonClick
    'TODO - Button Clicked - Execute Code Here
End Sub
```


[DataGridViewButtonColumn]: http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridviewbuttoncolumn.aspx
[CellClick]: http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridview.cellclick.aspx
[CellContentClick]: http://msdn.microsoft.com/en-us/library/system.windows.forms.datagridview.cellcontentclick.aspx


I am developing a windows application using C#. I am using `DataGridView` to display data. I have added a button column in that. I want to know how can I handle click event on that button in `DataGridView`.

How to handle click event in Button Column in Datagridview?

For anyone who is AutoGenerating their columns (*or even if you're not*), you can call this extension method on your `DataGridView` to resize the last column to `Fill`

**C-Sharp**:



    public static class Utilities
    {
        public static void StretchLastColumn(this DataGridView dataGridView)
        {
            var lastColIndex = dataGridView.Columns.Count - 1;
            var lastCol = dataGridView.Columns[lastColIndex];
            lastCol.AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;
        }
    }

**Visual Basic:**



    Public Module Utilities
    
        <Extension()>
        Public Sub StretchLastColumn(ByVal dataGridView As DataGridView)
            Dim lastColIndex = dataGridView.Columns.Count - 1
            Dim lastCol = dataGridView.Columns.Item(lastColIndex)
            lastCol.AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill
        End Sub
    
    End Module

I have a `DataGridView` with 5 columns, with `dock = filled`. 

I want the last (rightmost) column's width to fill the remaining right side of the form, when the form is maximized. 

How can I do that?


How the Rightmost column of a DataGridView could fill the remaining part of the form?

If Angshuman Agarwal's answer doesn't work for you, the culprit is likely that after load some control in the form is receiving focus, which will scroll into view and override any changes to the scroll position.

You *could* set `TabStop` to false, but then your form wouldn't be tabbable :(

A clunky work-around, but still relatively simple fix, is manually fire focus on the first control in your form:

```cs
yourFirstControl1.Select();
```

*See also*: [How to make the panel scroll bar to be at the TOP position on loading the form][1]

[1]: https://stackoverflow.com/q/1141778/1366033



I'm working on winfom application c#.
I have two forms called `Welome` and `Details`.
Details contains 7 grids in the Panel.

**Scenario:**
If I click on any of the item on welcome page it will take to the Details page with seven grids. If I drag the scroll bar down, and come back after moving back to welcome form, still the scroll bar stays at the same position.

**Question:**
I want to reset the scroll position to top each time the user visits the details form, so that I can always see first grid.


Reset the panel scroll position in winform application c#

If you want to continue using `AutoGenerateColumns = True` and `DataGridViewCheckBoxColumn`, you can modify the appearance and behavior to look and act like a read only field.

Assuming you wanted to target all CheckBoxCells, you can disable them and change their appearance like this:



    For Each row In DataGridView1.Rows.Cast(Of DataGridViewRow)()
        For Each cell In row.Cells.OfType(Of DataGridViewCheckBoxCell)()
            cell.ReadOnly = True
            cell.FlatStyle = FlatStyle.Flat
            cell.Style.ForeColor = Color.DarkSlateGray
        Next
    Next

I have a lot of read-only data, and I don't like the clickable look and feel of `DataGridViewCheckBoxColumn`s  which are unfortunately the default type for rendering Boolean data.

Is there any way, either before or after using `AutoGenerateColumns` of a `DataGridView` that I can force it to generate `DataGridViewTextBoxColumns` that would just print `TRUE` or `FALSE` instead of `DataGridViewCheckBoxColumns`?

![Sample of way Data currently is returned][screenshot]

If it is easier to address this problem on the `DataTable` before setting it as the `DataSource`, that would be fine too.

  [screenshot]: http://i.stack.imgur.com/BShxM.png


Forcing AutoGenerateColumns to create DataGridViewTextBoxColumn for Boolean Data Types

That window is a pita but there isn't anything you can do to stop it from showing up.  

Note how the original TabPage control doesn't show up in the toolbox, it is only ever added by the custom designer for TabControl.  This is done by giving it the [ToolboxItem(false)] attribute.  And your nemesis, [Designer] attributes that select custom designers for both the TabControl and the TabPage classes.  You'd have to create your own ExtendedTabControl and make a designer for it.  This is not fun, the TabControlDesigner class is a rather elaborate designer.  It is also *internal* so you cannot derive from it.  Using a decompiler like Reflector or ILSpy is a way to peek at the code in those designers.  I cannot recommend this unless you have a large and demanding user base of picky paying programmers.

Writing code instead of trying to make this work at design time is feasible.  But do note that you have to TryCast() at runtime to convert the TabPage reference you get from the TabPages property to your derived class.

I'm trying to use the [`System.ComponentModel.DesignerCategory`](http://msdn.microsoft.com/en-us/library/system.componentmodel.designercategoryattribute.aspx) Attribtue to prevent an extended Tab Page componenet from automatically opening up in the designer.   The suggestions on other StackOverflow questions [1][Q1],[2][Q2],[3][Q3], don't seem to work.

**Here's the code on the component**




    <System.ComponentModel.DesignerCategory("Code")>
    Public Class ExtendedTabPage : Inherits Windows.Forms.TabPage

**Here's the code in my .vbproj file**





    <Compile Include="ExtendedTabPage.vb">
      <SubType>Component</SubType>
    </Compile>

I've tried initializaing the DesignerCategory Attribute with a `""` and also `"Code"`, doing rebuilds and reopening the solution, but I still get the screen below from  a double click on the component.  Do I have to remove the project SubType?  Will that affect the way the code compiles?


![Component Designer][1]


  [1]: http://i.stack.imgur.com/BjBil.png
  [Q1]: https://stackoverflow.com/questions/2138684/is-it-possible-to-tell-visual-studio-not-to-treat-a-source-file-as-a-component
  [Q2]: https://stackoverflow.com/questions/230146/is-there-an-attribute-i-can-add-to-a-class-so-it-will-be-edited-as-code-not-in
  [Q3]: https://stackoverflow.com/questions/1789603/visual-studio-make-view-code-default-using-attribute

System.ComponentModel.DesignerCategory("Code") Still Opening Designer

Why don't you make it as Sub ..

    Private Sub ComboValidated(sender As System.Object, e As System.EventArgs) _
        Handles ComboBox1.Validated
    
        InCBValidated()
    
    End Sub
    
    Sub InCBValidated()
    
        'Do Something Here
    
    End Sub

So you just call `InCBValidated()`

I have some logic being handled in the `Validated` event on a combobox, but would like it to trigger as soon as a selection is made.  I can handle the `SelectedIndexChanged` event separately in order to fire the event, but I'm not sure how to invoke it.



    Private Sub ComboSelectedIndexChanged(sender As System.Object, e As System.EventArgs) _
        Handles ComboBox1.SelectedIndexChanged
        'Fire Validated Event
    End Sub

    Private Sub ComboValidated(sender As System.Object, e As System.EventArgs) _
        Handles ComboBox1.Validated
        'Do Something Here
    End Sub

  
I'd rather not call into the method handling the validated event directly,



    ComboValidated(Nothing, Nothing)

as it's not precisely what I'm trying to do with the code and it will run a second time when in fact the validated event actually does fire upon losing focus.

What code can I execute to fire the validated event (either by fire the event directly or by causing the control to lose focus)?

Fire Validated Event on WinForms ComboBox

I would set this up differently. You really shouldn't be changing your UI from your `SomeClass` object. It should just store data:

    Public Class SomeClass
    
        Private _someProperty As String = ""
    
        Public Property SomeProperty() As String
            Get
                Return _someProperty
            End Get
            Set(ByVal value As String)
                _someProperty = value
            End Set
        End Property
    
    End Class

Then, change your FormLoad and fix your data bindings so that everything is data bound:

    Private Sub FormLoad(sender As System.Object, e As System.EventArgs) _
          Handles MyBase.Load
        Dim data = {New With {.Display = "", .Value = ""},
                    New With {.Display = "A", .Value = "A"},
                    New With {.Display = "B", .Value = "B"},
                    New With {.Display = "C", .Value = "C"}}
    
        Label1.DataBindings.Add("Text", someClass, "SomeProperty");

        ComboBox1.DataSource = data
        ComboBox1.DisplayMember = "Display"
        ComboBox1.ValueMember = "Value"
        ComboBox1.DataBindings.Add("SelectedValue", someClass, "SomeProperty", 
              false, DataSourceUpdateMode.OnPropertyChanged)
    End Sub

Notice that above we bind `someClass` to your Label so that when the combobox is changed, the label will be updated.  

The final bit is to set the `DataSourceUpdateMode` on your combobox to OnPropertyChanged which will allow you to get rid of that event handler.

Better still, you should have `SomeClass` inherit from [INotifyPropertyChanged][1] because you are data binding it and you want to make sure that changes to SomeClass will have it notify the UI.

[1]:http://msdn.microsoft.com/en-us/library/system.componentmodel.inotifypropertychanged.aspx


I have a blank form, to which I've added a default `ComboBox`, `TextBox` (just for receiving focus), and `Label`.  The combobox has a databinding set up to a private property on the form.

**Setup:**



    Private Sub FormLoad(sender As System.Object, e As System.EventArgs) _
          Handles MyBase.Load
        Dim data = {New With {.Display = "", .Value = ""},
                    New With {.Display = "A", .Value = "A"},
                    New With {.Display = "B", .Value = "B"},
                    New With {.Display = "C", .Value = "C"}}

        ComboBox1.DataSource = data
        ComboBox1.DisplayMember = "Display"
        ComboBox1.ValueMember = "Value"
        ComboBox1.DataBindings.Add("SelectedValue", someClass, "SomeProperty")
    End Sub

Where someClass is a private variable of type `SomeClass` below:



	Public Class SomeClass

		Private _someProperty As String = ""

		Public Property SomeProperty() As String
			Get
				Return _someProperty
			End Get
			Set(ByVal value As String)
				_someProperty = value
				Form1.Label1.Text = String.Format("Some property = ""{0}""", value)
			End Set
		End Property

	End Class

**Expected Behavior:**

The default [`Binding.DataSourceUpdateMode`](http://msdn.microsoft.com/en-us/library/system.windows.forms.binding.datasourceupdatemode.aspx) is that changes will be propagated `OnValidation`.

If I select a value from the `ComboBox` and then click off it onto the `TextBox`, then the DataBinding will write the new value to the specified property and the Label on my main form will be updated.

**Possible Bug:**

The problem comes in because we have a business rule that requires us to perform validation immediately when a selection is made.  In order for validation to fire, the ComboBox has to lose focus, so by adding the following code to the `SelectionChangeCommitted` event, we can programmatically force validation



    Private Sub ComboChanged(sender As System.Object, e As EventArgs) _
            Handles ComboBox1.SelectionChangeCommitted
        TextBox1.Focus()
    End Sub

The problem is that this breaks the databinding for the very first selection.  The combobox has definitely lost focus, it definitely has a new `SelectedValue` and validation has definitely fired, but the databinding did not write the new value to `SomeProperty` on `someClass` (The setter never fires and the label, in this example, doesn't update).  In subsequent selections, the setter will fire

If necessary, from the `ComboBox1.SelectionChangeCommitted` event, I'll manually write the databinding, but feel like this is extra work since I need to process code during the Validation Event as well.



    ComboBox1.DataBindings.Item("SelectedValue").WriteValue()

**Questions:**

* *Shouldn't programmatically and manually losing focus do the same thing?*
* *Why does this work on subsequent selections, but not on the first one?*
* *Is this in fact some bug in WinForms, or have i done something horribly wrong?*

**Update:**

Thanks for the answers so far.  I guess I was looking more for an explanation than a workaround.  Why would it be the case that a bound property that updates on validation doesn't update even when the control has validated.  Further, why would it not happen the first time, but work for all future events?

Combobox DataBinding Bug - Won't write value if programmatically losing focus

Using a [`DateTimePickerFormat`][1] with [`.CustomFormat = "HH:mm:ss"`][1.1] is probably the best out of the box approach, but can be restrictive in terms of UI interaction. 

For people coming here looking for adding validation to a [`MaskedTextBox`][2], there are several good options.

### Type Validation

If you still want automatic parsing, you can can add a [`ValidatingType`][2.1] and tap into the [`TypeValidationCompleted`][2.2] Event like this:



    Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
            MaskedTextBox1.Mask = "00:00"
            MaskedTextBox1.ValidatingType = GetType(DateTime)
    End Sub

    Private Sub MaskedTextBox1_TypeValidationCompleted(sender As Object, e As TypeValidationEventArgs) _
        Handles MaskedTextBox1.TypeValidationCompleted
        If Not e.IsValidInput Then
            Me.validationToolTip.ToolTipTitle = "Invalid Time"
            Me.validationToolTip.Show("The time you supplied must be a valid time in the format HH:mm", sender)
        End If
    End Sub

`ValidatingType` will tap into the `public static Object Parse(string)` method for each type it's passed.  You can even pass in your own custom classes as long as they implement this signature

### Custom Validation:

To provide your own custom validation, you can tap into the [`Validating`][2.3] Event like this:



    Private Sub MaskedTextBox1_Validating(sender As System.Object, e As System.ComponentModel.CancelEventArgs) _
        Handles MaskedTextBox1.Validating
        Dim senderAsMask = DirectCast(sender, MaskedTextBox)
        Dim value = senderAsMask.Text
        Dim parsable = Date.TryParse(value, New Date)

        If Not parsable Then
            e.Cancel = True
            Me.validationToolTip.ToolTipTitle = "Invalid Time"
            Me.validationToolTip.Show("The time you supplied must be a valid time in the format HH:mm", sender)
        End If
    End Sub

In this case, the validation implementation is still rather naive, but you could implement whatever logic you want to determine validity. 

> **Notes**:  
>If the `CausesValidation` property is set to **false**, the `Validating` and `Validated` events are suppressed.  
>If the `Cancel` property of the `CancelEventArgs` is set to **true** in the Validating event delegate, all events that would usually occur after the `Validating` event are suppressed.

For Bonus Points, hide the tooltip when the user starts typing again:



    Private Sub MaskedTextBox1_KeyDown(ByVal sender As Object, ByVal e As KeyEventArgs) _
        Handles MaskedTextBox1.KeyDown
        Me.validationToolTip.Hide(sender)
    End Sub

[1]: https://msdn.microsoft.com/en-us/library/system.windows.forms.datetimepicker
[1.1]: https://msdn.microsoft.com/en-us/library/system.windows.forms.datetimepicker.customformat

[2]: https://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox
[2.1]: https://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.validatingtype
[2.2]: https://msdn.microsoft.com/en-us/library/system.windows.forms.maskedtextbox.typevalidationcompleted
[2.3]: https://msdn.microsoft.com/en-us/library/system.windows.forms.control.validating

My requirement is that the user will enter a time ("HH:mm:ss") in masked text box and based on that time i am doing some functionalities. My problem is i can mask the time but i can't restrict the user to enter up to 23 for hours,59 for minutes and 59 for seconds.
How to fix this.

**C# Code**

 

    private void Form1_Load(object sender, EventArgs e)
     {
    	maskTxtAlert1.Mask = "00:00:00";
            maskTxtAlert1.CutCopyMaskFormat = MaskFormat.ExcludePromptAndLiterals;
     }
    
     private void maskTxtAlert1_MaskInputRejected(object sender, MaskInputRejectedEventArgs e)
     {
                if (e.Position == maskTxtAlert1.Mask.Length)
               {
                   string errorMessage = "You cannot add extra characters";
                   toolTip1.ToolTipTitle = "Input Rejected - No more inputs allowed";
                   toolTip1.Show(errorMessage, maskTxtAlert1, 12, 24, 2000);
                   errorProvider1.BlinkStyle = ErrorBlinkStyle.AlwaysBlink;
                   errorProvider1.SetError(maskTxtAlert1, errorMessage);
               }
               else
               {
                   toolTip1.ToolTipTitle = "Input Rejected";
                   string errorMessage = "You can only add numeric characters (0-9).";
                   toolTip1.Show(errorMessage, maskTxtAlert1, 12, 24, 2000);
                   errorProvider1.BlinkStyle = ErrorBlinkStyle.AlwaysBlink;
                   errorProvider1.SetError(maskTxtAlert1, errorMessage);
               }
       }
    
     private void maskTxtAlert1_TypeValidationCompleted(object sender, TypeValidationEventArgs e)
     {
               MessageBox.Show("Enter Valid as One");
     }

How to restrict values in Winforms MaskedTextbox

ClickOnce doesn't pass through standard command line args, but through the [ActivationArguments][1] instead.

Your file info should be available via 
`AppDomain.CurrentDomain.SetupInformation.ActivationArguments.ActivationData`


  [1]: https://msdn.microsoft.com/en-us/library/system.runtime.hosting.activationarguments.activationdata(v=vs.110).aspx

I'm trying to associate an application with a particular file type and then use that file when the application starts up. It's pretty trivial to [Create File Associations For a ClickOnce Application][File Association]:

![Publish Options > File Associations][Publish Options]


This currently works, so if I have an file with the extension ".tester," my Click Once Deployed application will fire up.

The problem I'm having trouble with is *identifying which file launched the application*.

According to the question [What Event is Triggered When Opening a Custom File?][Open File Event], the "file should be available from the command line args", and this [Scott Hanselman Article confirms][Hanselman].

However, when I add the following code, I don't get anything besides the path to the executable when firing the application.



    Dim args = Environment.GetCommandLineArgs()
    MsgBox(Join(args, ", "))

![Command Line Args][args 1]

I have confirmed that I'm fetching all the command line arguments.  When I launch the file from the actual command line with some bogus arguments:



    C:\FileHandler.exe -foo bar

The application will display the following: 

![args 2][args 2]

**How do I identify the file that initiated the application?**


[File Association]: https://msdn.microsoft.com/en-us/library/bb892924.aspx
[Publish Options]: http://i.stack.imgur.com/DfH6T.png
[Open File Event]: https://stackoverflow.com/q/16476182/1366033

[Hanselman]: http://www.hanselman.com/blog/TheWeeklySourceCode31SingleInstanceWinFormsAndMicrosoftVisualBasicdll.aspx
[args 1]: http://i.stack.imgur.com/H289G.png
[args 2]: http://i.stack.imgur.com/yV5NT.png

How do I identify the file that launched my application

If you're getting the following error `unable to resolve 'clr'`:

[![Example Error][0]][0]

It's likely that you don't have a python interpreter *installed* or *configured* for Visual Studio

Per the question [The environment ironpython 2.7-32 appears to be incorrectly configured or missing][1a]

> The Visual Studio Installer does *not* include an IronPython Package option to install

So you need to: 

1. [Download IronPython from Github][1] and install it
2. Then, select the correct [Python environment within your VS project][2].

[0]: https://i.stack.imgur.com/BZqff.png
[1a]: https://stackoverflow.com/q/46045103/1366033
[1]: https://github.com/IronLanguages/ironpython2/releases/
[2]: https://learn.microsoft.com/en-us/visualstudio/python/managing-python-environments-in-visual-studio?view=vs-2019#the-python-environments-window
[3]: https://learn.microsoft.com/en-us/visualstudio/python/managing-python-environments-in-visual-studio?view=vs-2019#manually-identify-an-existing-environment






 

Steps to reproduce:

1. I created a new project in Visual Studio
2. Selected Python > Desktop > "IronPython Windows Forms Application"

However, as soon as I open the project I encountered several errors which I don't know how to solve. The errors are unresolved import clr an similar. 



[![Brand New Windows Forms Python Project][1]][1]


  [1]: https://i.stack.imgur.com/h0EFH.png

Windows Forms in Visual Studio with Python

1. Right click the DataGridView and select Edit Columns

   [![Edit Columns][1]][1]

2. Select the DefaultCellStyle Property and click on the Style Wizard


   [![DefaultCellStyle][2]][2]

3. In the CellStyle Builder window, you can set whatever properties you'd like, including `BackColor`

   [![CellStyle Builder][3]][3]

What this will do is set the property inside of the *form.designer.cs* file during `InitializeComponent()`

    
```cs
private void InitializeComponent()
{
    /// ...
    this.ShadedColumn.DefaultCellStyle.BackColor = Color.Silver;
    /// ...
}
```
<sup>\* where *`this.ShadedColumn`* is the name of the `DataGridViewTextBoxColumn` control you added</sup>

Any code in `InitializeComponent` will execute during the designer view, and technically you *can* update most styles directly here, but it's advised to use the GUI form builder to make any changes against this file

**Further Reading**: [Set Default Cell Styles and Data Formats for the Windows Forms DataGridView Control Using the Designer][4]


  [1]: https://i.stack.imgur.com/InyMd.png
  [2]: https://i.stack.imgur.com/xS67i.png
  [3]: https://i.stack.imgur.com/dxlCN.png
  [4]: https://learn.microsoft.com/en-us/dotnet/framework/winforms/controls/default-cell-styles-datagridview

There's a question about [changing cell background color in a DataGridView][1] programatically

But is there any way to set the background color for a particular column  *using the WinForms Designer*?


[1]: https://stackoverflow.com/q/16105718/1366033