FIxes a dumb wallpaper bug when using i3 with MATE

refresh_wall_on_display_change_mate.c

#include <stdio.h>
#include <stdlib.h>

#include <X11/X.h>
#include <X11/Xlib.h>
#include <X11/extensions/Xrandr.h>

static XEvent xEvent;
static Display *XDisplay;
static Screen *XScreen;
static Window XRoot;

static Bool xavaSupportsRR;
static int xavaRREventBase;

static int XScreenNumber;

int init_window_x(void) {
	// connect to the X server
	XDisplay = XOpenDisplay(NULL);
	if(XDisplay == NULL) {
		fprintf(stderr, "cannot open X display\n");
		return 1;
	}

	XScreen = DefaultScreenOfDisplay(XDisplay);
	XScreenNumber = DefaultScreen(XDisplay);
	XRoot = RootWindow(XDisplay, XScreenNumber);

	XStoreName(XDisplay, XRoot, "Dumb wallpaper fixer 9000");
	XSelectInput(XDisplay, XRoot, RRScreenChangeNotifyMask | VisibilityChangeMask | StructureNotifyMask | ExposureMask | KeyPressMask | KeymapNotify);

	// query for the RR extension in X11
	int error;
	xavaSupportsRR = XRRQueryExtension(XDisplay, &xavaRREventBase, &error);
	if(xavaSupportsRR) {
		int rr_major, rr_minor;

		if(XRRQueryVersion(XDisplay, &rr_major, &rr_minor)) {
			int rr_mask = RRScreenChangeNotifyMask;
			if(rr_major == 1 && rr_minor <= 1) {
				rr_mask &= ~(RRCrtcChangeNotifyMask |
					RROutputChangeNotifyMask |
					RROutputPropertyNotifyMask);
			}

			// listen for display configure events only if enabled
			XRRSelectInput(XDisplay, XRoot, rr_mask);
		}
	}
	return 0;
}

void draw_graphical_x(void) {
	XSync(XDisplay, 0);
	return;
}

void cleanup_graphical_x(void) {
	// make sure that all events are dead by this point
	XSync(XDisplay, 1);

	XCloseDisplay(XDisplay);
	return;
}

int main(int argc, char *argv[]) {
	init_window_x();
	while(1) {
		XNextEvent(XDisplay, &xEvent);
		if(xEvent.type == xavaRREventBase + RRScreenChangeNotify) {
			printf("Display change detected - Fixing wallpaper...\n");
			// this is done by simply toggling it off and on
			system("gsettings set org.mate.background draw-background false");
			system("gsettings set org.mate.background draw-background true");
		}
		draw_graphical_x();
	}

	// this is never run, lol
	cleanup_graphical_x();
	return 0;
}