Desktop: Focus app window when loading a document (#4124)

desktop/src/app.rs

@@ -368,6 +368,11 @@ impl App {
 					window.start_drag();
 				}
 			}
+			DesktopFrontendMessage::WindowFocus => {
+				if let Some(window) = &self.window {
+					window.focus();
+				}
+			}
 			DesktopFrontendMessage::WindowHide => {
 				if let Some(window) = &self.window {
 					window.hide();

desktop/src/window.rs

@@ -140,6 +140,11 @@ impl Window {
 		let _ = self.winit_window.drag_window();
 	}
 
+	pub(crate) fn focus(&self) {
+		self.winit_window.set_minimized(false);
+		self.winit_window.focus_window();
+	}
+
 	pub(crate) fn hide(&self) {
 		self.native_handle.hide();
 	}