added epi::Frame::set_window_pos (#1505)

this allows setting the position of window at runtime

egui-winit/src/epi.rs

@@ -96,6 +96,7 @@ pub fn handle_app_output(
         window_title,
         decorated,
         drag_window,
+        window_pos,
     } = app_output;
 
     if let Some(decorated) = decorated {
@@ -116,6 +117,13 @@ pub fn handle_app_output(
         window.set_title(&window_title);
     }
 
+    if let Some(window_pos) = window_pos {
+        window.set_outer_position(winit::dpi::PhysicalPosition {
+            x: window_pos.x as f64,
+            y: window_pos.y as f64,
+        });
+    }
+
     if drag_window {
         let _ = window.drag_window();
     }