UI: Check to ensure window starts up inside a monitor

Fixes an issue where the main window would load off-screen if its last
saved position was inside a monitor that no longer exists.

obs/obs-app.cpp

@@ -1483,6 +1483,23 @@ bool GetClosestUnusedFileName(std::string &path, const char *extension)
 	return true;
 }
 
+bool WindowPositionValid(int x, int y)
+{
+	vector<MonitorInfo> monitors;
+	GetMonitors(monitors);
+
+	for (auto &monitor : monitors) {
+		int br_x = monitor.x + monitor.cx;
+		int br_y = monitor.y + monitor.cy;
+
+		if (x >= monitor.x && x < br_x &&
+		    y >= monitor.y && y < br_y)
+			return true;
+	}
+
+	return false;
+}
+
 static inline bool arg_is(const char *arg,
 		const char *long_form, const char *short_form)
 {

obs/obs-app.hpp

@@ -147,6 +147,8 @@ inline const char *Str(const char *lookup) {return App()->GetString(lookup);}
 bool GetFileSafeName(const char *name, std::string &file);
 bool GetClosestUnusedFileName(std::string &path, const char *extension);
 
+bool WindowPositionValid(int x, int y);
+
 static inline int GetProfilePath(char *path, size_t size, const char *file)
 {
 	OBSMainWindow *window = reinterpret_cast<OBSMainWindow*>(

obs/window-basic-main.cpp

@@ -132,6 +132,9 @@ OBSBasic::OBSBasic(QWidget *parent)
 		int posy = config_get_int(App()->GlobalConfig(), "BasicWindow",
 				"posy");
 
+		if (!WindowPositionValid(posx, posy))
+			posx = posy = 0;
+
 		setGeometry(posx, posy, width, height);
 	}