<Swing Dev> [PATCH] DefaultDesktopPane fix

[Alexander Potochkin]

Hello Roman

> I found a problem in DefaultDesktopPane. Dragging in fast mode does not
> work correctly (at least not on all platforms) if the pane is obscured
> by another heavyweight. Graphics.copyArea() isn't guaranteed to work
> correctly in this case. 

This looks like a bug to me,
could you please provide a small test case to illustrate this problem
with Graphics.copyArea()?

if this is a bug we should fix it rather then workaround it
with a new method

Would you agree?

Thanks
alexp


> I think we need to do like in JViewport and
> check if the heavyweight is guaranteed to be not obscured and only do
> the fast dragging if this is the case. I pulled the checking code from
> JViewport to SwingUtilities so they can share this thing.
> 
> I know this is a corner case, because in most cases, when dragging an
> internal frame, the user clicks on the frame and brings the window to
> the top anyway, so it should not be obscured, but there could be
> always-on-top dialogs or similar, which stay on top of the app, even
> when the user drags something.
> 
> The webrev is here:
> 
> http://kennke.org/~roman/desktoppane/webrev/
> 
> What do you think? Should this be included in OpenJDK?
> 
> /Roman
>