wmaker: make the '--replace' de-activable at compile time

As it is really unlikely that in normal use case someone would need this
feature, it is now conditional code, which is not enabled by default; the
configure scripts now propose a '--enable-wmreplace' option to enable the
corresponding code, as people making package for distributions may want to
enable the feature to provide users the ability to give a try of all the
window managers.

Suggested-by: Carlos R. Mafra <crmafra@gmail.com>
Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

configure.ac

@@ -526,6 +526,20 @@ AS_IF([test "x$enable_xdnd" = "xyes"],
 AM_CONDITIONAL([USE_DOCK_XDND], [test "x$enable_dock_xdnd" != "xno"])
 
 
+dnl Support for ICCCM 2.0 Window Manager replacement
+dnl ================================================
+AC_ARG_ENABLE([wmreplace],
+    [AS_HELP_STRING([--enable-wmreplace], [support for ICCCM window manager replacement])],
+    [AS_CASE([$enableval],
+        [yes|no], [],
+        [AC_MSG_ERROR([bad value '$enableval' for --enable-wmreplace])])],
+    [enable_wmreplace=no])
+AS_IF([test "x$enable_wmreplace" = "xyes"],
+    [AC_DEFINE([USE_ICCCM_WMREPLACE], [1],
+       [define to support ICCCM protocol for window manager replacement])
+     supported_xext="$supported_xext WMReplace"])
+
+
 dnl XShape support
 dnl ==============
 AC_ARG_ENABLE([shape],

doc/build/Compilation.texi

@@ -575,6 +575,12 @@ Disable support for Motif's MWM Window Manager hints.
 These attributes were introduced by the Motif toolkit to ask for special window appearance requests.
 Nowadays this is covered by the NetWM/EWMH specification, but there are still applications that rely on MWM Hints.
 
+@item --enable-wmreplace
+Add support for the @emph{ICCCM} protocol for cooperative window manager replacement.
+This feature is disabled by default because you probably don't need to switch seamlessly the window manager;
+if you are making a package for a distribution you'd probably want to enable this because it allows users to give
+a try to different window managers without restarting everything for an extra cost that is not really big.
+
 @item --disable-xdnd
 Disable support for dragging and dropping files on the dock, which launches a user-specified command
 with that file.

src/WindowMaker.h

@@ -463,7 +463,9 @@ extern struct WPreferences {
 	char show_clip_title;
 
 	struct {
+#ifdef USE_ICCCM_WMREPLACE
 		unsigned int replace:1;               /* replace existing window manager */
+#endif
 		unsigned int nodock:1;                /* don't display the dock */
 		unsigned int noclip:1;                /* don't display the clip */
 		unsigned int clip_merged_in_dock:1;   /* disable clip, switch workspaces with dock */

src/event.c

@@ -1894,6 +1894,7 @@ static void handleVisibilityNotify(XEvent * event)
 
 static void handle_selection_clear(XSelectionClearEvent *event)
 {
+#ifdef USE_ICCCM_WMREPLACE
 	WScreen *scr = wScreenForWindow(event->window);
 
 	if (!scr)
@@ -1904,4 +1905,11 @@ static void handle_selection_clear(XSelectionClearEvent *event)
 
 	wmessage(_("another window manager is replacing us!"));
 	Shutdown(WSExitMode);
+#else
+	/*
+	 * If the support for ICCCM window manager replacement was not enabled, we should not receive
+	 * this kind of event, so we simply do nothing.
+	 */
+	(void) event;
+#endif
 }

src/main.c

@@ -435,7 +435,9 @@ static void print_help(void)
 	puts(_("The Window Maker window manager for the X window system"));
 	puts("");
 	puts(_(" -display host:dpy	display to use"));
+#ifdef USE_ICCCM_WMREPLACE
 	puts(_(" --replace		replace running window manager"));
+#endif
 	puts(_(" --no-dock		do not open the application Dock"));
 	puts(_(" --no-clip		do not open the workspace Clip"));
 	puts(_(" --no-autolaunch	do not autolaunch applications"));
@@ -652,8 +654,10 @@ static int real_main(int argc, char **argv)
 				wPreferences.flags.noclip = 1;
 			} else if (strcmp(argv[i], "-nodrawer") == 0 || strcmp(argv[i], "--no-drawer") == 0) {
 				wPreferences.flags.nodrawer = 1;
+#ifdef USE_ICCCM_WMREPLACE
 			} else if (strcmp(argv[i], "-replace") == 0 || strcmp(argv[i], "--replace") == 0) {
 				wPreferences.flags.replace = 1;
+#endif
 			} else if (strcmp(argv[i], "-version") == 0 || strcmp(argv[i], "--version") == 0) {
 				printf("Window Maker %s\n", VERSION);
 				exit(0);

src/screen.c

@@ -66,7 +66,9 @@
     |SubstructureRedirectMask|ButtonPressMask|ButtonReleaseMask\
     |KeyPressMask|KeyReleaseMask)
 
+#ifdef USE_ICCCM_WMREPLACE
 #define REPLACE_WM_TIMEOUT 15
+#endif
 
 #define STIPPLE_WIDTH 2
 #define STIPPLE_HEIGHT 2
@@ -108,6 +110,7 @@ static void make_keys(void)
  */
 static Bool replace_existing_wm(WScreen *scr)
 {
+#ifdef USE_ICCCM_WMREPLACE
 	char atomName[16];
 	Window wm;
 	XSetWindowAttributes attribs;
@@ -139,10 +142,12 @@ static Bool replace_existing_wm(WScreen *scr)
 		if (!XChangeWindowAttributes(dpy, wm, CWEventMask, &attribs))
 			wm = None;
 	}
+#endif
 
 	/* for our window manager info notice board and the selection owner */
 	scr->info_window = XCreateSimpleWindow(dpy, scr->root_win, 0, 0, 10, 10, 0, 0, 0);
 
+#ifdef USE_ICCCM_WMREPLACE
 	/* Try to acquire the selection */
 	current_time = CurrentTime;
 	ret = XSetSelectionOwner(dpy, scr->sn_atom, scr->info_window, current_time);
@@ -188,6 +193,7 @@ static Bool replace_existing_wm(WScreen *scr)
 	event.data.l[4] = (long) 0L;
 	event.window = scr->root_win;
 	XSendEvent(dpy, scr->root_win, False, StructureNotifyMask, (XEvent *) &event);
+#endif
 
 	return True;
 }

src/screen.h

@@ -69,7 +69,9 @@ typedef struct WDrawerChain {
 typedef struct _WScreen {
     int	screen;			       /* screen number */
     Window info_window;		       /* for our window manager info stuff */
+#ifdef USE_ICCCM_WMREPLACE
     Atom sn_atom;		       /* window manager selection */
+#endif
 
     int scr_width;		       /* size of the screen */
     int scr_height;