[Gambas-user] User control disappears when moved by mouse

[Claus Dietrich]

When I move a user control (.i.e. a button ) on its form with following code

Public Sub Button1_MouseMove()

   If Mouse.left = True Then
      Button1.Move(Mouse.screenx - Mouse.startx + Mouse.X, Mouse.Screeny 
- Mouse.StartY + Mouse.y)
   End If

End

the user control disappears at some positions and when I lift the mouse 
button in such a moment the user control disappears completely. That 
means, that it is not displayed any longer and also stops to raise mouse 
events.

It happens on Mint Cinnamon, Mate an Kubuntu and also with labels, no 
matter whether I use QT or GTK. Is it a bug? What can be done to avoid 
this behaviour?

Best regards

Claus