Transparent PNG Form background doesn't update

[LiQuick]

Dear readers,

When I use a Transparent PNG as a form's background I can see through
the form (which is the intention). But when I move the form the
see-through part of the background is not updated. It looks like the
region behind the form is being copied onto the form's background and
the PNG is merged ontop of this copy. How can I force this copying?

Best Regards,
Rémy Samulski

 

[LiQuick]

Dear Ciaran,

Thanks for your reply. You're right about the moving and dotnet not
invalidating the form. But invalidating or refreshing the form doesn't
solve the problem. I have made some screenshots to illustrate the
problem:
1) http://www.LiQuick.net/images/temp/Transparent01.jpg shows that the
transparent PNG works as a standard background and shows the desktop
with proper alpha blending.
2) Refreshing and or invalidating the form does repaint the PNG but
more or less untop of the already placed background.
http://www.LiQuick.net/images/temp/Transparent02.jpg As you can see the
shadow of the form has darkened due to numerous repaints ontop of the
background of the form. (hopefully I'm clear about what I'm saying).
3) Furthermore moving other forms on top of the form makes them leave
trails behind I can't get rid of except minimizing, maximizing or
hiding the form. http://www.LiQuick.net/images/temp/Transparent03.jpg

Who can help me repaint the background from scratch and not as I think
is handled by dotnet as grabbing the current background and merging the
png ontop of it.

Rémy Samulski

 

[LiQuick]

Not really but have found another way to do what I wanted. Look at this
article: http://www.codeproject.com/useritems/How_to_make_VistaForm.asp

Greets
Rémy