Your code works fine for me:
kde:
openbox + xcompmgr:
Most likely you are not running composite manager. Try to start xcompmgr
command
Also check _NET_WM_CM_S0
selection owner - it should point to a window created by composite manager.
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <stdio.h>
int main(int argc, char* argv[])
{
Display* display = XOpenDisplay(NULL);
Atom cmAtom = XInternAtom(display, "_NET_WM_CM_S0", 0);
Window cmOwner = XGetSelectionOwner(display, cmAtom);
printf("Composite manager window: %i\n", cmOwner);
XCloseDisplay(display);
return 0;
}
Update:
Try to set override-redirect to prevent WM decorations from obscuring your window.
attr.border_pixel = 0;
attr.background_pixel = 0;
attr.override_redirect = 1; /* this line added */
Window win = XCreateWindow(display, DefaultRootWindow(display), 0, 0, 300, 200, 0,
vinfo.depth, InputOutput, vinfo.visual,
CWColormap | CWBorderPixel | CWBackPixel | CWOverrideRedirect /* and this one*/, &attr);