Revert "app: optimize window context locking"

This reverts commit 3e601e73c4 because it
results in a blank window on Android.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
Fixes: https://todo.sr.ht/~eliasnaur/gio/671

app/window.go

@@ -142,11 +142,8 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 		if w.gpu == nil && !w.nocontext {
 			var err error
 			if w.ctx == nil {
-				if w.ctx, err = w.driver.NewContext(); err != nil {
+				w.ctx, err = w.driver.NewContext()
-					return err
+				if err != nil {
-				}
-				if err = w.ctx.Lock(); err != nil {
-					w.destroyGPU()
 					return err
 				}
 				sync = true
@@ -166,6 +163,12 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 				return err
 			}
 		}
+		if w.ctx != nil {
+			if err := w.ctx.Lock(); err != nil {
+				w.destroyGPU()
+				return err
+			}
+		}
 		if w.gpu == nil && !w.nocontext {
 			gpu, err := gpu.New(w.ctx.API())
 			if err != nil {
@@ -197,6 +200,7 @@ func (w *Window) validateAndProcess(size image.Point, sync bool, frame *op.Ops,
 		var err error
 		if w.gpu != nil {
 			err = w.ctx.Present()
+			w.ctx.Unlock()
 		}
 		return err
 	}