[AD] Strange palettes under Windows 7 RTM

[John Murphy <wonsungi@xxxxxxxxxx>]

Hello,

I'd like to report some strangeness with Allegro palettes under Windows 7.

I am fairly certain it is an Allegro/Win7 problem, since it occurs with the example programs from Allegro 4.2.3

Repro steps:

run exflame

Expected:

White text on black; flame colored gradient palette

Actual:

Momentarily white text on maroon; flame colored gradient palette, but unusual purple/yellow outline

After 1 or 2 seconds: Blue text on maroon; entire flame lacks "fire" palette: all purple/yellow

Notes:

Repros with several, but not all of the allegro examples. Mostly limited to 8-bit palette programs, although one of my own programs repros in all color depths.

Environment:

Allegro 4.2.3

Visual Studio Express 2008

Windows 7 RTM
Lenovo Thinkpad X301 (integrated graphics==Intel X4500)

When I used Allegro (4.2.?) under Vista I did not see this problem at all.

I think Windows 7 is preventing Allegro from fully controlling the screen palette.

I did some further experimentation with my own programs:

My own fire program has a graphics mode selection dialog and takes a pcx screen capture.

- It also displays palette problems, but only in 8-bit fullscreen modes. 8-bit windowed/16+bit full screen modes have no problems.

- Even though the screen palette does not look right, the pcx screen capture is good.

- By constantly setting the palette each frame, the problem can be mostly fixed. There are still some artifacts of a bad palette.

Another program, asteroids, displays palette problems in any graphics mode.

- The pcx screen capture also shows a messed up palette

- I double-checked the DAT file, and the palette and graphics look fine in the grabber tool.

- Constantly setting the palette each frame does not help at all in this case

Both these programs worked without palette problems under Vista + Allegro (4.2.?)

Please advise how to debug this type of problem.

I have not been able to test on a non-Windows 7 machine, but I have a feeling it only repros on Windows 7.

- The Allegro example programs have palette problems, which probably would have been noticed by others already

- My own programs started showing palette problems, although the only change was Vista->Win7 (and possibly a minor Allegro version change)

Thanks~

John