Drag and Drop Problem

[mob4l]

Hello all.

I have a portion of code that allows the user to drag items from one ListBox control and drop them onto another ListBox control. Up until a few days ago, I was using Visual Basic 2003 to develop this project. At that time, the drag and drop code was working. After purchasing and installing Visual Basic 2005, I converted my project to the new format. Now that I have converted, the drag and drop portion of my code no longer works.

Here is a description of the problem:

I click an item in the source ListBox and begin a drag. The mouse cursor becomes a circle with a slash through it, indicating an invalid drop target. The problem is that whenever I drag the cursor over the destination list box, the cursor never changes to indicate a valid drag target. The AllowDrop property is set in the destination list box.

Here is the code I have for drag and drop concerning the source and destination list boxes. StockItemBox is the source ListBox, StockItemCategoryBox is the destination ListBox.

Private Sub StockItemBox_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles StockItemBox.MouseDown

        If StockItemBox.SelectedIndex < 0 Then Exit Sub

        Dim DragText As String = StockItemBox.Items(StockItemBox.SelectedIndex)

        StockItemBox.DoDragDrop(DragText, DragDropEffects.Move)

    End Sub

Private Sub StockItemCategoryBox_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles StockItemCategoryBox.DragEnter

        If (e.Data.GetDataPresent(DataFormats.Text)) Then
            ' Display the copy cursor.
            e.Effect = DragDropEffects.Copy
        Else
            ' Display the no-drop cursor.
            e.Effect = DragDropEffects.None
        End If

    End Sub

Private Sub StockItemCategoryBox_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles StockItemCategoryBox.DragDrop

        'extract the dropped text
        Dim TextDropped As String = e.Data.GetData(DataFormats.Text).ToString

        MsgBox(TextDropped)

    End Sub

The StockItemCategoryBox_DragDrop method is never called.

I'm not sure if it makes a difference, but the form that these controls are located on is displayed using a ShowDialog call.

Anyone have any suggestions? Is there something I am missing here? It is weird that the code worked fine with the 2003 project but not the newly converted project.

[jmcilhinney]

What is the second argument of the DoDragDrop method called? It's called 'allowedEffects'. What effects are you saying are allowed? You'r saying that Move and Move only is allowed. Then when you enter the drop target you're trying to set the effect to Copy. Copy is not Move so it's not allowed.