SV: Window questions

I am using SDL_SetVideoMode() with flags SDL_RESIZABLE and
SDL_SWSURFACE to create a small resizable window.

Does anybody know if you can prevent the window manager from supplying a
border to the window ? (my bitmap supplies it’s own window border).

Speaking only for X11 (which is what I know about), this is somewhat
against its philosophy. The Window Manager is supposed to decorate windows,
not the clients, so that all windows can be controlled (resized, moved,
closed etc) in the same way. Some WMs can be hinted to remove part or whole
of the decoration, but there is no standard way to do this.

By setting the override-redirect flag you can create windows that completely
bypass the WM; this is primarily used for short-lived UI windows such as
pop-up menus.

Finally, is it possible to make the window always stay on top of all
other application windows?

In X11 there is no such mechanism other than keeping an eye on a window
and raising it when obscured. This is considered a bad idea because of
the calamity when running two of those at the same time. Normally the
user overlaps windows for a reason, and finds it most disturbing if the
application should not obey his command.

MacOS has “floating” or “palette” windows, which form an independent
layer above normal windows. X11 has no such mechanism, though it would
certainly be possible to implement it as a policy on the WM level.
As far as I know, nobody has done so yet, but I often find myself wishing
for it when using Gimp.

IceWM lets you place windows in special levels to keep them above (or under) other windows. This feature probably exists in other WMs too.