Bitmap of a button pulses when button has focus

[catalin]

Looks like there is yet another state for a button, PBS_STYLUSHOT.
Although  MS docs say it "is used only on tablet computers", not providing an image for that state will make the image keep appearing and disappearing under Win7.

[catalin]

File icon_cross.png used in the test code is attached to #11476

[vadz]

Excellent, thanks a lot for finding this!

I don't want to modify the State enum as it's supposed to represent a state which can be passed to Do{Get,Set}Bitmap() and this is not the case for this one under non-MSW, so I'll apply it in a slightly different form but the important thing was, of course, finding the real reason for this bug.

Thanks again!

[VZ]

(In [73486]) Fix pulsing of bitmaps in focused buttons under Windows 7.

It turns out that the actual bitmap shown in this case varies between the
bitmaps at PBS_DEFAULTED and PBS_STYLUSHOT, so that it's invisible half of the
time if we don't specify the value for the latter. Do it now to fix unwanted
pulsing of the bitmap in the focused button.

Closes #15034.