When running Firefox 4.0b8pre (20101112 nightly) on Windows 2003 R2 Service Pack 2, if you use the "XP" Theme that comes with the OS instead of the "Classic" theme, the Minimize/Maximize/Close buttons and, in the most recent nightly, the Firefox button also, are way too tall. Switching to the no application button (turning back on "Menu Bar") seems to fix it. With the "Classic" theme, either works as expected. Pictures attached.

Stretched buttons with App button and XP theme

Just tried it on our base VM image of 2003 that we use for deployments. Same issue there, so it's definitely consistent on all 2003 installs (this image is absolutely base aside from SP2 and all latest updates applied). Thanks. Also, isn't related at all to Hardware Acceleration. Exhibits the same effect either enabled or disabled.

Yeah, like I thought, this started showing up as soon as the Firefox App Button got placed in the titlebar (Beta 5). Everything since then exhibits this behavior ON WINDOWS 2003. XP seems fine.

It began on the 08/26 nightly, which appears to be the first time that button in the titlebar was enabled for XP/2003. Hope that helps.

Correcting comment #6, it was actually the 08/25 nightly. Still the first time that the Firefox Button was placed into the titlebar on XP/2003 though. Got the date wrong above.

Maybe bug 615890 is somehow related (Windows XP with Windows Embedded Standard theme, having a too tall application button).

Yeah, that looks like the exact same problem as we're seeing. Question... do the min/max/close buttons also appeared stretched vertically as I showed in the screenshots?

No, they don't. That's why I filed an extra bug. Maybe I should have mentioned it there.

Turned out to be somehow tied to a long forgotten uxtheme.dll patch that had been installed to make custom theming work on the platform. Evidently it didn't remove itself properly when it was uninstalled way back when.