ui: Bug fix: ScreenSizeFullscreen before Run crashes on Linux

internal/ui/ui_glfw.go

@@ -41,6 +41,8 @@ type userInterface struct {
 	windowWidth          int
 	height               int
 	initMonitor          *glfw.Monitor
+	initFullscreenWidth  int
+	initFullscreenHeight int
 
 	scale           float64
 	fullscreenScale float64
@@ -99,6 +101,10 @@ func initialize() error {
 	// TODO: Fix this hack. currentMonitorImpl now requires u.window on POSIX.
 	currentUI.window = w
 	currentUI.initMonitor = currentUI.currentMonitorImpl()
+	v := currentUI.initMonitor.GetVideoMode()
+	s := glfwScale()
+	currentUI.initFullscreenWidth = int(float64(v.Width) / s)
+	currentUI.initFullscreenHeight = int(float64(v.Height) / s)
 	currentUI.window.Destroy()
 	currentUI.window = nil
 
@@ -236,18 +242,17 @@ func (u *userInterface) setInitIconImages(iconImages []image.Image) {
 
 func ScreenSizeInFullscreen() (int, int) {
 	u := currentUI
+	if !u.isRunning() {
+		return u.initFullscreenWidth, u.initFullscreenHeight
+	}
+
 	var v *glfw.VidMode
 	s := 0.0
-	if u.isRunning() {
 	_ = mainthread.Run(func() error {
 		v = u.currentMonitor().GetVideoMode()
 		s = glfwScale()
 		return nil
 	})
-	} else {
-		v = currentUI.initMonitor.GetVideoMode()
-		s = glfwScale()
-	}
 	return int(float64(v.Width) / s), int(float64(v.Height) / s)
 }