Skeleton for debugging focus problems with X11 window managers

x11-focus-tests.c

#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>

Display *dpy;
Window rootwin;
Atom atom_WM_NAME;
Window appwin;
Window childwin;

static void fill_rect(Window win, unsigned long color, int x, int y, int width, int height)
{
        XGCValues values;
        unsigned long valuemask;
        GC gc;

        valuemask = GCForeground;
        values.foreground = color;
                
        gc = XCreateGC(dpy, win, valuemask, &values);

        XClearWindow(dpy, win);
        XFillRectangle(dpy, win, gc, x, y, width, height);

        XFreeGC(dpy, gc);
}

static void set_class_hint(Window win, const char *res_name, const char *res_class)
{
        XClassHint *hint = XAllocClassHint();
        hint->res_name = (char *) res_name;
        hint->res_class = (char *) res_class;

        XSetClassHint(dpy, win, hint);

        XFree(hint);
}

static void set_wm_name(Window win, const char *wmname)
{
        XTextProperty prop;
        XmbTextListToTextProperty(dpy, (char **)&wmname, 1, XStringStyle, &prop);
        XSetWMName(dpy, win, &prop);

        XFree(prop.value);
}

static void set_wm_hints(Window win)
{
        XWMHints *wmhints = XAllocWMHints();

        wmhints->flags = InputHint;
        wmhints->input = True;

        XSetWMHints(dpy, win, wmhints);

        XFree(wmhints);
}

static void set_transient_for(Window win, Window owner)
{
        XSetTransientForHint(dpy, win, owner);
}

int main(void)
{
        dpy = XOpenDisplay(NULL);
        rootwin = DefaultRootWindow(dpy);

        atom_WM_NAME = XInternAtom(dpy, "WM_NAME", False);

        appwin = XCreateSimpleWindow(
                        dpy, rootwin, 200, 200, 400, 400, 1,
                        XBlackPixel(dpy, rootwin),
                        XBlackPixel(dpy, rootwin));

        childwin = XCreateSimpleWindow(
                        dpy, appwin, 250, 250, 300, 300, 1,
                        XBlackPixel(dpy, rootwin),
                        XBlackPixel(dpy, rootwin));

        XSelectInput(dpy, appwin, ExposureMask);
        XSelectInput(dpy, childwin, ExposureMask);

        set_wm_name(appwin, "MyTestProg");
        set_class_hint(appwin, "foo", "bar");
        set_wm_hints(appwin);

        set_wm_name(childwin, "child window");
        set_transient_for(childwin, appwin);

        XMapWindow(dpy, appwin);
        XMapWindow(dpy, childwin);

        XSync(dpy, False);

        while (1) {
                XEvent xev;
                XNextEvent(dpy, &xev);

                switch (xev.type) {
                case Expose:
                        fill_rect(appwin, 0xBEBEBE, 50, 50, 1000, 1000);
                        fill_rect(childwin, 0x00FF00, 0, 0, 1000, 1000);
                        break;
                }
        }

        return 0;
}