Why would GDI+ colours vary based off whether a tooltip is visible?
- by dlanod
I'm displaying a bitmap using GDI+. After loading the bitmap from a DLL resource I set the background colour (blue - #0000FF) to transparent using TransparentBlt. On Windows Vista and later this works as expected.
However, on a Windows XP system we're testing on this only works when any tooltip (e.g. the "title" property in IE, or Windows Explorer's tooltip shown when hovering the mouse over a file, etc) is displayed. The rest of the time the background colour is still blue.
Has anyone encountered this before, or know of a way to stop this occurring and for the blue to be properly made transparent?