The tab frame is drawn behind the tabs.
Create a new DrawTabFrame method in BControlLook and HaikuControlLook
that draws the tab frame background.
Until now we've been reusing the DrawInactiveTab method to draw the tab frame
in BTabView. While this works on HaikuControlLook, it doesn't work on other
ControlLook's (such as BeControlLook) that draw their tab frame differently.
Add FBC method to preserve binary compatibility on gcc2 and gcc4.
Move DrawTabFrame method to where _ReservedControlLook1 was in header.
Set rect to area of tab frame in TabView instead of doing the
calculation in HaikuControlLook so that others may benefit.
Change-Id: I513e238914f6d680f495659b6ec902df15555015
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1936
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
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