Create main window at 0,0 if its the same size as the display

This fixes #1051 by explicity telling SDL to create the window in the
display corner instead of centering the window. This has caused some
problems because the window borders aren't visible anymore in this case
which lead to some confusion.

Author: asarium

freespace2/SDLGraphicsOperations.cpp

@@ -163,9 +163,28 @@ std::unique_ptr<os::Viewport> SDLGraphicsOperations::createViewport(const os::Vi
 		windowflags |= SDL_WINDOW_RESIZABLE;
 	}
 
+	SDL_Rect bounds;
+	if (SDL_GetDisplayBounds(props.display, &bounds) != 0) {
+		mprintf(("Failed to get display bounds: %s\n", SDL_GetError()));
+		return nullptr;
+	}
+
+	int x;
+	int y;
+
+	if (bounds.w == (int)props.width && bounds.h == (int)props.height) {
+		// If we have the same size as the desktop we explicitly specify 0,0 to make sure that the window borders aren't hidden
+		mprintf(("SDL: Creating window at %d,%d because window has same size as desktop.\n", bounds.x, bounds.y));
+		x = bounds.x;
+		y = bounds.y;
+	} else {
+		x = SDL_WINDOWPOS_CENTERED_DISPLAY(props.display);
+		y = SDL_WINDOWPOS_CENTERED_DISPLAY(props.display);
+	}
+
 	SDL_Window* window = SDL_CreateWindow(props.title.c_str(),
-										  SDL_WINDOWPOS_CENTERED_DISPLAY(props.display),
-										  SDL_WINDOWPOS_CENTERED_DISPLAY(props.display),
+										  x,
+										  y,
 										  props.width,
 										  props.height,
 										  windowflags);