MainNoGUI: Supply a window in Host_GetRenderHandle

Our existing code was relying on the GLX backend to create the GLX
window properly, and for the rest of the code to patch that up, sort
of. If we rely on Host_GetRenderHandle() returning a valid window, we
can do a lot better about this.

Create a simple window inside MainNoGUI to make this happen.

Source/Core/DolphinWX/GLInterface/GLX.cpp

@@ -67,8 +67,6 @@ bool cInterfaceGLX::Create(void *&window_handle)
 	GLWin.dpy = XOpenDisplay(nullptr);
 	GLWin.parent = (Window)window_handle;
 	GLWin.screen = DefaultScreen(GLWin.dpy);
-	if (GLWin.parent == 0)
-		GLWin.parent = RootWindow(GLWin.dpy, GLWin.screen);
 
 	glXQueryVersion(GLWin.dpy, &glxMajorVersion, &glxMinorVersion);
 	NOTICE_LOG(VIDEO, "glX-Version %d.%d", glxMajorVersion, glxMinorVersion);

Source/Core/DolphinWX/GLInterface/X11_Util.cpp

@@ -13,7 +13,7 @@ void cX11Window::CreateXWindow(void)
 	// Setup window attributes
 	GLWin.attr.colormap = XCreateColormap(GLWin.dpy,
 			GLWin.parent, GLWin.vi->visual, AllocNone);
-	GLWin.attr.event_mask = KeyPressMask | StructureNotifyMask | FocusChangeMask;
+	GLWin.attr.event_mask = StructureNotifyMask;
 	GLWin.attr.background_pixel = BlackPixel(GLWin.dpy, GLWin.screen);
 	GLWin.attr.border_pixel = 0;
 
@@ -24,7 +24,6 @@ void cX11Window::CreateXWindow(void)
 			CWBorderPixel | CWBackPixel | CWColormap | CWEventMask, &GLWin.attr);
 	wmProtocols[0] = XInternAtom(GLWin.dpy, "WM_DELETE_WINDOW", True);
 	XSetWMProtocols(GLWin.dpy, GLWin.win, wmProtocols, 1);
-	XSetStandardProperties(GLWin.dpy, GLWin.win, "GPU", "GPU", None, nullptr, 0, nullptr);
 	XMapRaised(GLWin.dpy, GLWin.win);
 	XSync(GLWin.dpy, True);
 

Source/Core/DolphinWX/MainNoGUI.cpp

@@ -52,9 +52,10 @@ void Host_Message(int Id)
 	}
 }
 
+void* windowHandle;
 void* Host_GetRenderHandle()
 {
-	return nullptr;
+	return windowHandle;
 }
 
 void Host_UpdateTitle(const std::string& title){};
@@ -129,6 +130,7 @@ void Host_ShowVideoConfig(void*, const std::string&, const std::string&) {}
 class PlatformX11 : public Platform
 {
 	Display *dpy;
+	Window win;
 	Cursor blankCursor = None;
 #if defined(HAVE_XRANDR) && HAVE_XRANDR
 	X11Utils::XRRConfiguration *XRRConfig;
@@ -138,12 +140,17 @@ class PlatformX11 : public Platform
 	{
 		XInitThreads();
 		dpy = XOpenDisplay(NULL);
-	}
 
-	void MainLoop() override
-	{
-		Window win = (Window)Core::GetWindowHandle();
+		win = XCreateSimpleWindow(dpy, DefaultRootWindow(dpy),
+					  SConfig::GetInstance().m_LocalCoreStartupParameter.iRenderWindowXPos,
+					  SConfig::GetInstance().m_LocalCoreStartupParameter.iRenderWindowYPos,
+					  SConfig::GetInstance().m_LocalCoreStartupParameter.iRenderWindowWidth,
+					  SConfig::GetInstance().m_LocalCoreStartupParameter.iRenderWindowHeight,
+					  0, 0, BlackPixel(dpy, 0));
 		XSelectInput(dpy, win, KeyPressMask | FocusChangeMask);
+		XMapRaised(dpy, win);
+		XFlush(dpy);
+		windowHandle = (void *) win;
 
 		if (SConfig::GetInstance().m_LocalCoreStartupParameter.bDisableScreenSaver)
 			X11Utils::InhibitScreensaver(dpy, win, true);
@@ -163,7 +170,10 @@ class PlatformX11 : public Platform
 			XFreePixmap (dpy, Blank);
 			XDefineCursor(dpy, win, blankCursor);
 		}
+	}
 
+	void MainLoop() override
+	{
 		bool fullscreen = SConfig::GetInstance().m_LocalCoreStartupParameter.bFullscreen;
 
 		if (fullscreen)