[PATCH v2] comctl32: Correctly draw disabled toolbar button which contains 32 bpp bitmap with alpha channel.

[Ziqing Hui]

v2: check has_alpha in imagelist.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=24784
Signed-off-by: Ziqing Hui 
---
 dlls/comctl32/imagelist.c |  5 +++++
 dlls/comctl32/toolbar.c   | 12 ++++++++++++
 include/commctrl.h        |  2 ++
 3 files changed, 19 insertions(+)