[Comctl32] - Transparent icons gets opaque when "delete" dialog box is displayed in Explorer

reactos-livecd-0.4.15-dev-6772-gc03b2ed-x86-gcc-lin-dbg
reactos-livecd-0.4.15-dev-6773-g855008d-x86-gcc-lin-dbg

Guilty commit : https://github.com/reactos/reactos/commit/855008d97b2c7e1a1b72ad268b68d83c739ebc6d from StartForKiller while fixing CORE-16722

Maybe related to the "double redraw" mentioned by reactosfanboy in CORE-19519

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• Open Explorer with a folder containings transparent icons

• Attempt to delete a file to get the confirmation message box
• While message box is displayed, transparent icons are drawn as opaque

Regression as it was OK on reactos-livecd-0.4.15-dev-2205-g880252f-x86-gcc-lin-dbg