Themes: disabled items on menus were using a color mix of text and text_selected, this didn't work nice with dark themes and text shadows and overall didn't make much sense.
Now, disabled items use a mix of text and menu item background (inner) color. Same results, but allows dark themes with bright selected text to use shadows.

Example case: http://pasteall.org/pic/show.php?id=45697





git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54641 954f8c5b-7b00-dc11-b283-0030488c597c