DOCUMENT:Q184206  20-APR-1998  [vbwin]
TITLE   :PRB: DragDrop with ListView Control Fails in MouseMove Event
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:5.0
OPER/SYS:WINDOWS
KEYWORDS:vb5all

======================================================================
---------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   for Windows, version 5.0
---------------------------------------------------------------------

SYMPTOMS
========

In a ListView control, if you have DragMode set to vbManual and attempt to
begin DragDrop within the MouseMove event, the Drag operation will never
begin if the View property is set to either lvwIcon or lvwSmallIcon. The
Drag operation will begin successfully if the View property is set to
lvwList or lvwReport.

CAUSE
=====

Normally, the way to initiate an ordinary DragDrop procedure is to set the
Drag property of the Listview control to vbBeginDrag. This is done by
detecting the state of the left-mouse button. If it is depressed, set the
Drag property accordingly. However, this will not work if you place your
code in the MouseMove event. When the left-mouse button is depressed, the
MouseMove button never fires, which means you can't test for the left-mouse
button's state and consequently are not able to begin the Drag operation.
This is only the case when the Listview control's View property is set to
either lvwIcon or lvwSmallIcon. If it is set to lvwList or lvwReport, the
code works as expected.

RESOLUTION
==========

Add code to begin the Drag operation in the MouseDown event. The event is
always fired when the left-mouse button is clicked.

STATUS
======

Microsoft is researching this problem and will post new information here in
the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Start with a Visual Basic form (Form1) and add four Command Buttons and
   two ListView controls.

2. Place the following code in the General Declarations section of Form1:

      Option Explicit

      Private Sub Command1_Click()
          ListView1.View = lvwIcon
      End Sub

      Private Sub Command2_Click()
          ListView1.View = lvwSmallIcon
      End Sub

      Private Sub Command3_Click()
          ListView1.View = lvwList
      End Sub

      Private Sub Command4_Click()
          ListView1.View = lvwReport
      End Sub

      Private Sub Form_Load()
          Dim Li As ListItem
          Dim colX As ColumnHeader

          Set colX = ListView1.ColumnHeaders.Add()
          colX.Text = "Field "
          colX.Width = ListView1.Width

          Set Li = ListView1.ListItems.Add(, , "hello")
          Set Li = ListView1.ListItems.Add(, , "hello2")
          Set Li = ListView1.ListItems.Add(, , "hello3")

          Command1.Caption = "lvwIcon"
          Command2.Caption = "lvwSmallIcon"
          Command3.Caption = "lvwList"
          Command4.Caption = "lvwReport"
      End Sub

      Private Sub ListView1_MouseMove(Button As Integer, _
              Shift As Integer, x As Single, y As Single)

      If Button = vbLeftButton Then
         Set ListView1.SelectedItem = ListView1.HitTest(x, y)
         ' In the following line any ICO file will do
         ListView1.DragIcon = LoadPicture( _
              "C:\program files\devstudio\vb\samples\pguide\calc\calc.ico")
         ListView1.Drag vbBeginDrag
      End If
      End Sub

      Private Sub ListView2_DragDrop(Source As Control, x As Single, _
              y As Single)
         Dim li2 As ListItem

         MsgBox "Hello"
         Set li2 = ListView2.ListItems.Add(, , Source.SelectedItem.Text)
      End Sub

3. Run the program by pressing the F5 key.

4. Try a Drag procedure with the Listview control set to lvwIcon or
   lvwSmallIcon. Note that the mouse pointer is stuck within the Listview
   client area. Change the View property to lvwList or lvwReport and note
   that the Drag operation works as expected.

Additional query words: list view drag drop drag drop
======================================================================
Keywords          : vb5all
Version           : WINDOWS:5.0
Platform          : WINDOWS
Issue type        : kbprb

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1998.