Hello Andreas,
How are you doing?

Regarding the issue that you have raised relating to the refreshing or the
pge in IE when the mouse moves back to the browser.

I tried replicating the scenario, and was somewhat successful. If I do
nothing in my drop event and just use e = e.empty in drop event of a text
box.
I can see what you are experiencing. To solve this I replaced the following
code:
e=e.Empty
with
e=nothing

Here is my code snippet for the drop text box:

Private Sub TextBox2_DragEnter(ByVal sender As Object, ByVal e As
System.Windows.Forms.DragEventArgs) Handles TextBox2.DragEnter
       If (e.Data.GetDataPresent(DataFormats.Text)) Then
          e.Effect = DragDropEffects.Copy
       Else
           e.Effect = DragDropEffects.None
       End If
       End Sub

   Private Sub TextBox2_DragDrop(ByVal sender As Object, ByVal e As
System.Windows.Forms.DragEventArgs) Handles TextBox2.DragDrop
       'TextBox2.Text = e.Data.GetData(DataFormats.Text).ToString
       'e = e.Empty 'This recreates the issue
       e = nothing 'Solves the issue

   End Sub

I hope this helps.

Thanks
Mona
[Grapecity]