Question

Edit: Assume a TextBox as the control for the example – where height is not an issue

So I am using the mouse to change a control’s width and location at runtime (through grabbing a handle with a mouse, much the same way that you can change it at design time). However, I am noticing some resizing issues, which I thought would be fixed by calling

<panel>.SuspendLayout
<control>.location = new Point(x, y)
<control>.width = newWidth
<panel>.ResumeLayout

Now both the location and width change correctly, but because the location changes first – you see a blur of the textbox changing width after it moves. Now reading through Suspend and ResumeLayout, I guess they are supposed to be called before the controls are constructed. With that being the case: how do I make sure the location and width change at once to avoid the blur?

Edit: Solved – The following code allowed me to suspend drawing the control before the properties were set, then resume afterward. As opposed to suspending the layout*

Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hWnd As Integer, _
                                                                ByVal wMsg As Integer, _
                                                                ByVal wParam As Integer,
                                                                ByVal lParam As Integer) As Integer

Private Const WM_SETREDRAW As Integer = 11

' Extension methods for Control
<Extension()>
Public Sub ResumeDrawing(ByVal Target As Control, ByVal Redraw As Boolean)
  SendMessage(Target.Handle, WM_SETREDRAW, 1, 0)
  If Redraw Then
    Target.Refresh()
  End If
End Sub

<Extension()>
Public Sub SuspendDrawing(ByVal Target As Control)
  SendMessage(Target.Handle, WM_SETREDRAW, 0, 0)
End Sub

<Extension()>
Public Sub ResumeDrawing(ByVal Target As Control)
  ResumeDrawing(Target, True)
End Sub

Answer 1

Instead of panel.SuspendLayout(), do this.SuspendLayout(). Suspend and Resume are guaranteed to traverse down the actual object tree, but I’ve never had luck with it trickling down the container tree.