Why does Button.DoubleClick not fire in WinForms when MouseUp opens another form?

Hi @test code ,

Thanks for reaching out.

The Button.DoubleClick event often doesn’t fire if the first click changes the UI, such as opening a new form, because a double-click requires two consecutive clicks on the same button. In your case, the first click opens a new form, so the second click lands on that new form instead, and the double-click event never gets triggered.

Also, as noted in the official docs (thanks to Castorix31 for pointing this out; see the Remarks section here: Button.DoubleClick), WinForms buttons don’t have the standard double-click behavior enabled by default. Internally, the ControlStyles.StandardClick and ControlStyles.StandardDoubleClick bits are false for Button, which is why the DoubleClick event isn’t reliably raised. While it’s technically possible to change these style bits in a custom button, doing so is rarely practical and doesn’t solve scenarios where the first click changes the UI (like opening a form).

A clean and reliable way to handle single vs double clicks is to use the MouseUp event and inspect e.Clicks. For example:

Private Sub Button1_MouseUp(sender As Object, e As MouseEventArgs) Handles Button1.MouseUp
    If e.Button = MouseButtons.Left Then
        If e.Clicks = 2 Then
            ' Double-click action
            MsgBox("Double click detected!")
        ElseIf e.Clicks = 1 Then
            ' Single-click action
            Dim form = New Form1
            form.ShowDialog()
            form.Dispose()
        End If
    End If
End Sub

Hope this helps! If my answer was helpful - kindly follow the instructions here so others with the same problem can benefit as well.

Why isn't the Button1.DoubleClick event called on double clicking the button?

It is explained in Remarks : https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.button.doubleclick?view=windowsdesktop-10.0&redirectedfrom=MSDN#remarks

You must change the style...

The behavior you're observing occurs because the MouseUp event is processed before the DoubleClick event can be triggered. In Windows Forms, a double-click is recognized by the system based on the timing of two consecutive clicks. When you double-click the button, the first click triggers the MouseUp event, which opens another form. This interrupts the double-click detection, causing the second click to be processed as a single click on the newly opened form instead of being recognized as part of a double-click on the original button.

To handle this situation, you can modify your approach by using the Click event instead of MouseUp to open the new form. The Click event is fired after the double-click detection logic has completed, allowing the DoubleClick event to be triggered correctly. Here’s how you can adjust your code:

Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim form = New Form1
        form.ShowDialog()
        form.Dispose()
    End Sub

    Private Sub Button1_DoubleClick(sender As Object, e As EventArgs) Handles Button1.DoubleClick
        MsgBox("double click")
    End Sub

    Private Sub Form1_MouseUp(sender As Object, e As MouseEventArgs) Handles MyBase.MouseUp
        MsgBox("Mouse Up")
    End Sub
End Class

By using the Click event, you ensure that the double-click functionality works as intended, and the new form will open only when the button is clicked, not on the MouseUp event.

References:

• How to: Respond to Windows Forms Button Clicks
• Events overview