If I hold down the left or right mouse button, mouseenter doesn't work

I am making a game where you touch certain blocks with the mouse to score points, and others lose you the game. My friend found a bug where if you hold down the left or right mouse button, the computer will not detect either mouseenter events. Any help would be appreciated!

Solution

Assuming WinForms, when a control gets a MouseDown event from the user pressing a mouse button, it "captures" the mouse input from that moment until the mouse button is released. This is used to provide the MouseUp event even if the mouse moved away from the control.

You would have to override that but there is a side-effect:

Private Sub Panel1_MouseDown(sender As Object, e As MouseEventArgs) _
                                               Handles Panel1.MouseDown
  Panel1.Capture = False
End Sub

Now you have no guarantee the MouseUp event will fire unless the mouse is directly over the control.