How do I correctly set the xwindows properties - c

Question

Given the code:
/*
* XWindows study on if we can turn the frame on and off.
*/
#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAPIT
#define REPEAT
void waitxevt(Display* d, int type)
{
XEvent e; /* XEvent holder */
do { XNextEvent(d, &e); } while (e.type != type);
}
void frame(Display* d, Window w, int e)
{
Atom window_type;
long value;
#ifdef MAPIT
XUnmapWindow(d, w);
waitxevt(d, UnmapNotify);
#endif
window_type = XInternAtom(d, "_NET_WM_WINDOW_TYPE", False);
if (e) value = XInternAtom(d, "_NET_WM_WINDOW_TYPE_NORMAL", False);
else value = XInternAtom(d, "_NET_WM_WINDOW_TYPE_DOCK", False);
XChangeProperty(d, w, window_type, XA_ATOM, 32, PropModeReplace, (unsigned char *) &value, 1);
#ifdef MAPIT
XMapWindow(d, w);
waitxevt(d, MapNotify);
#endif
}
int main(void) {
Display* d;
Window w;
XEvent e;
const char* msg = "Hello, World!";
int s;
GC gracxt;
int frmenb = 0;
d = XOpenDisplay(NULL);
if (d == NULL) {
fprintf(stderr, "Cannot open display\n");
exit(1);
}
s = DefaultScreen(d);
gracxt = XDefaultGC(d, s);
w = XCreateSimpleWindow(d, RootWindow(d, s), 10, 10, 640, 480, 5,
BlackPixel(d, s), WhitePixel(d, s));
XSelectInput(d, w, ExposureMask|KeyPressMask|StructureNotifyMask);
XMapWindow(d, w);
waitxevt(d, MapNotify);
while (1) {
XNextEvent(d, &e);
if (e.type == Expose) XDrawString(d, w, gracxt, 10, 50, msg, strlen(msg));
if (e.type == KeyPress) {
frame(d, w, frmenb);
frmenb = !frmenb;
#ifdef REPEAT
frame(d, w, frmenb);
frmenb = !frmenb;
#endif
}
}
XCloseDisplay(d);
return 0;
}
The purpose of the code is to turn the frame on and off for the window w. With no map/unmap operation, The "off" call works correctly, and the window changes (onscreen) to have no frame, and is not sizable, and the titlebar no longer appears.
However, on turning it back on using the routine, the titlebar is not visible, but it is sizable. If you resize the window, the titlebars reappear.
The suggestion was made to unmap the window before setting the property and remap after. The result of this is that the window without frame no longer can have focus, and thus cannot get a key to change back. I put in a "repeat" flag to make it immediately revert back to full frame mode, and thus prove that the return to framing works. It does. Another side effect is that the position of the window gets reset after the map operation, but I can compensate for that.
This is on Ubuntu 20.04.
What is the purpose? This code is part of a toolkit to port between Windows and Linux. The frame on/off is used for two purposes (so far):
To make component windows (widgets) without frames.
To toggle the frame. For example, I have a clock program that if you click on it, it will remove the frame, making it both smaller and immobile. Another click restores it.
The first one works now, since it only turns off the frame once, and that happens before mapping. The second one does not work.
New program, now works, using the suggestions:
/*
* XWindows study on if we can turn the frame on and off.
*/
#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct MwmHints {
unsigned long flags;
unsigned long functions;
unsigned long decorations;
long input_mode;
unsigned long status;
};
enum {
MWM_HINTS_FUNCTIONS = (1L << 0),
MWM_HINTS_DECORATIONS = (1L << 1),
MWM_FUNC_ALL = (1L << 0),
MWM_FUNC_RESIZE = (1L << 1),
MWM_FUNC_MOVE = (1L << 2),
MWM_FUNC_MINIMIZE = (1L << 3),
MWM_FUNC_MAXIMIZE = (1L << 4),
MWM_FUNC_CLOSE = (1L << 5)
};
void frame(Display* d, Window w, int e)
{
Atom mwmHintsProperty;
struct MwmHints hints;
mwmHintsProperty = XInternAtom(d, "_MOTIF_WM_HINTS", 0);
hints.flags = MWM_HINTS_DECORATIONS;
hints.decorations = !!e;
XChangeProperty(d, w, mwmHintsProperty, mwmHintsProperty, 32,
PropModeReplace, (unsigned char *)&hints, 5);
}
int main(void) {
Display* d;
Window w;
XEvent e;
const char* msg = "Hello, World!";
int s;
GC gracxt;
int frmenb = 0;
d = XOpenDisplay(NULL);
if (d == NULL) {
fprintf(stderr, "Cannot open display\n");
exit(1);
}
s = DefaultScreen(d);
gracxt = XDefaultGC(d, s);
w = XCreateSimpleWindow(d, RootWindow(d, s), 10, 10, 640, 480, 5,
BlackPixel(d, s), WhitePixel(d, s));
XSelectInput(d, w, ExposureMask|KeyPressMask|StructureNotifyMask);
XMapWindow(d, w);
while (1) {
XNextEvent(d, &e);
if (e.type == Expose) XDrawString(d, w, gracxt, 10, 50, msg, strlen(msg));
if (e.type == KeyPress) {
frame(d, w, frmenb);
frmenb = !frmenb;
}
}
XCloseDisplay(d);
return 0;
}