Improvements to setTitle on Linux

WM_CLASS should not change after window creation. It's illegal (may only change while the window is in the Withdrawn state) and causes flickering issues on the taskbar.

The native setTitle implementation has been changed to use a better fallback when XChangeProperty fails and _NET_WM_ICON_NAME is also set, in addition to _NET_WM_NAME.

src/java/org/lwjgl/opengl/LinuxDisplay.java

@@ -787,9 +787,6 @@ public void setTitle(String title) {
 		} finally {
 			unlockAWT();
 		}
-
-		// also update the class hint value as some WM's use it for the window title
-		if (Display.isCreated()) setClassHint(title, wm_class);
 	}
 	private static native void nSetTitle(long display, long window, long title, int len);
 

src/native/linux/opengl/org_lwjgl_opengl_Display.c

@@ -174,15 +174,25 @@ static bool isLegacyFullscreen(jint window_mode) {
 }
 
 static void setWindowTitle(Display *disp, Window window, jlong title, jint len) {
+	Atom UTF8_STRING = XInternAtom(disp, "UTF8_STRING", True);
+	Atom _NET_WM_NAME = XInternAtom(disp, "_NET_WM_NAME", True);
+	Atom _NET_WM_ICON_NAME = XInternAtom(disp, "_NET_WM_ICON_NAME", True);
+
 	// ASCII fallback if XChangeProperty fails.
-	XStoreName(disp, window, (const char *)(intptr_t)title);
+    XmbSetWMProperties(disp, window, (const char *)(intptr_t)title, (const char *)(intptr_t)title, NULL, 0, NULL, NULL, NULL);
 
 	// Set the UTF-8 encoded title
-	XChangeProperty(disp, window,
-					XInternAtom(disp, "_NET_WM_NAME", False),
-					XInternAtom(disp, "UTF8_STRING", False),
-					8, PropModeReplace, (const unsigned char *)(intptr_t)title,
-					len);
+	if ( _NET_WM_NAME )
+		XChangeProperty(
+			disp, window, _NET_WM_NAME, UTF8_STRING,
+			8, PropModeReplace, (const unsigned char *)(intptr_t)title, len
+		);
+
+	if ( _NET_WM_ICON_NAME )
+		XChangeProperty(
+			disp, window, _NET_WM_ICON_NAME, UTF8_STRING,
+			8, PropModeReplace, (const unsigned char *)(intptr_t)title, len
+		);
 }
 
 static void setClassHint(Display *disp, Window window, jlong wm_name, jlong wm_class) {