BeOS didn't support transparent views. As documented in the Be Book,
SetViewColor(B_TRANSPARENT_COLOR) only effect is to not fill the
invalidated areas with the view color before calling Draw() (it avoids
flickering, especially when combined with B_FULL_UPDATE_ON_RESIZE).
A previous change made B_TRANSPARENT_COLOR actually make the view
transparent (that is, additionally to the above, the underlying view is
drawn before the transparent children), but it creates compatibility
issues.
In order to keep the API compatible with BeOS, the new behavior is now
enabled explicitly using the B_TRANSPARENT_VIEW flag. This also opens
for future developments like allowing a view color with an alpha
channel (not supported yet).
Adjust programs that require transparent views.
Fixes#15744, #15745.
Helps with #15645.
Change-Id: I529574ea23db0a23579521b263bc8d572775e35a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2275
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
47102c0742