WaitCursor and mouse locked in QueryContinueDrag

20 Aug 2006 3:43 PM

Roberto Reale

While developing a drag&drop enabled application I found out this
"strange" behaviour: if I put a message box into the QueryContinueDrag
event handler the message box is shown but the mouse cursor is set to
WaitCursor (Hourglass) and I can't click on OK or on X, so that the
only way to close the message box is via the keyboard, by pressing
SPACE key.

The most strange thing is that if I place two message boxes, only the
first one is affected by the issue described: it seems that the
unloading of the first message box someway "resets" the mouse.

The steps to reproduce this are simple:

1)      Create a new Windows Forms Project
2)      Place a ListView control on the form
3)      Paste the following code:

====8<===CODE================================

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

        ListView1.View = View.List
        ListView1.Items.Add("test")

    End Sub

    Private Sub ListView1_ItemDrag(ByVal sender As Object, ByVal e As
System.Windows.Forms.ItemDragEventArgs) Handles ListView1.ItemDrag

        If e.Button = Windows.Forms.MouseButtons.Left Then
            ListView1.DoDragDrop("something to drag",
DragDropEffects.Move)
        End If

    End Sub

    Private Sub ListView1_QueryContinueDrag(ByVal sender As Object,
ByVal e As System.Windows.Forms.QueryContinueDragEventArgs) Handles
ListView1.QueryContinueDrag

        If e.Action = DragAction.Drop Then
            MsgBox("First Message") 'press SPACEBAR to hide this
            MsgBox("Second message") 'this can be hidden the usual
way
        End If

    End Sub

====8<===CODE - END==========================

4)      Run the application
3)      Try to drag&drop the "test" item somewhere

I'm using Visual Studio 2005 ver. 8.0.50727.42

Any Suggestion?

Thanks

Roberto

20 Aug 2006 5:34 PM

tommaso.gastaldi@uniroma1.it

I have the same version. There is no difference between the 2 msgboxes:
I need to press enter in either case.

Tommaso

Roberto Reale ha scritto:

Show quoteHide quote

> While developing a drag&drop enabled application I found out this
> "strange" behaviour: if I put a message box into the QueryContinueDrag
> event handler the message box is shown but the mouse cursor is set to
> WaitCursor (Hourglass) and I can't click on OK or on X, so that the
> only way to close the message box is via the keyboard, by pressing
> SPACE key.
>
> The most strange thing is that if I place two message boxes, only the
> first one is affected by the issue described: it seems that the
> unloading of the first message box someway "resets" the mouse.
>
>
> The steps to reproduce this are simple:
>
>
> 1)      Create a new Windows Forms Project
> 2)      Place a ListView control on the form
> 3)      Paste the following code:
>
>
> ====8<===CODE================================
>
>
>     Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles MyBase.Load
>
>
>         ListView1.View = View.List
>         ListView1.Items.Add("test")
>
>
>     End Sub
>
>
>     Private Sub ListView1_ItemDrag(ByVal sender As Object, ByVal e As
> System.Windows.Forms.ItemDragEventArgs) Handles ListView1.ItemDrag
>
>
>         If e.Button = Windows.Forms.MouseButtons.Left Then
>             ListView1.DoDragDrop("something to drag",
> DragDropEffects.Move)
>         End If
>
>
>     End Sub
>
>
>     Private Sub ListView1_QueryContinueDrag(ByVal sender As Object,
> ByVal e As System.Windows.Forms.QueryContinueDragEventArgs) Handles
> ListView1.QueryContinueDrag
>
>
>         If e.Action = DragAction.Drop Then
>             MsgBox("First Message") 'press SPACEBAR to hide this
>             MsgBox("Second message") 'this can be hidden the usual
> way
>         End If
>
>
>     End Sub
>
>
> ====8<===CODE - END==========================
>
>
> 4)      Run the application
> 3)      Try to drag&drop the "test" item somewhere
>
>
> I'm using Visual Studio 2005 ver. 8.0.50727.42
>
>
> Any Suggestion?
>
>
> Thanks
>
>
> Roberto

21 Aug 2006 2:44 PM

Roberto Reale

I finally worked it out!

I found out that when QueryContinueDrag is fired, mouse control is not
automatically given to the form. This must be done manually, by setting the
"Capture" property to True for the form itself.

For the sample project used in this thread, the QueryContinueDrag becomes:

====8<===CODE================================

Private Sub ListView1_QueryContinueDrag(ByVal sender As Object, ByVal e As
System.Windows.Forms.QueryContinueDragEventArgs) Handles
ListView1.QueryContinuedrag

         If e.Action = DragAction.Drop Then

         Me.Capture = True ' <- gains mouse control

             MsgBox("First Message") 'press SPACEBAR to hide this
             MsgBox("Second message") 'this can be hidden the usual way
         End If

End Sub

====8<===CODE - END============================

I'd like to stress that I found this solution on my own, not on official
documentation (except for the "Capture" property reference), so I can't
assure that this is the best/officially suggested solution to this issue. It
works anyway :-)

Hope this helps!

Roberto

Show quoteHide quote

"tommaso.gasta***@uniroma1.it" wrote:

> I have the same version. There is no difference between the 2 msgboxes:
> I need to press enter in either case.
>
> Tommaso
>
> Roberto Reale ha scritto:
>
> > While developing a drag&drop enabled application I found out this
> > "strange" behaviour: if I put a message box into the QueryContinueDrag
> > event handler the message box is shown but the mouse cursor is set to
> > WaitCursor (Hourglass) and I can't click on OK or on X, so that the
> > only way to close the message box is via the keyboard, by pressing
> > SPACE key.
> >
> > The most strange thing is that if I place two message boxes, only the
> > first one is affected by the issue described: it seems that the
> > unloading of the first message box someway "resets" the mouse.
> >
> >
> > The steps to reproduce this are simple:
> >
> >
> > 1)      Create a new Windows Forms Project
> > 2)      Place a ListView control on the form
> > 3)      Paste the following code:
> >
> >
> > ====8<===CODE================================
> >
> >
> >     Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
> > System.EventArgs) Handles MyBase.Load
> >
> >
> >         ListView1.View = View.List
> >         ListView1.Items.Add("test")
> >
> >
> >     End Sub
> >
> >
> >     Private Sub ListView1_ItemDrag(ByVal sender As Object, ByVal e As
> > System.Windows.Forms.ItemDragEventArgs) Handles ListView1.ItemDrag
> >
> >
> >         If e.Button = Windows.Forms.MouseButtons.Left Then
> >             ListView1.DoDragDrop("something to drag",
> > DragDropEffects.Move)
> >         End If
> >
> >
> >     End Sub
> >
> >
> >     Private Sub ListView1_QueryContinueDrag(ByVal sender As Object,
> > ByVal e As System.Windows.Forms.QueryContinueDragEventArgs) Handles
> > ListView1.QueryContinueDrag
> >
> >
> >         If e.Action = DragAction.Drop Then
> >             MsgBox("First Message") 'press SPACEBAR to hide this
> >             MsgBox("Second message") 'this can be hidden the usual
> > way
> >         End If
> >
> >
> >     End Sub
> >
> >
> > ====8<===CODE - END==========================
> >
> >
> > 4)      Run the application
> > 3)      Try to drag&drop the "test" item somewhere
> >
> >
> > I'm using Visual Studio 2005 ver. 8.0.50727.42
> >
> >
> > Any Suggestion?
> >
> >
> > Thanks
> >
> >
> > Roberto
>
>