Resolves: fdo#31306 some icons don't get grayed when disabled
Resolves: fdo#31306 some icons don't get grayed when disabled

some of our menu icons are not RGBA, but our fade-out code only
handled images with an alpha channel, so we need to extend it
for bitmaps with alpha channel icons

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core