Fix dragging of `custom_window_frame` example on Windows (#4656)

* Related #4592 
* Closes #4647 

Fix dragging of custom_window_frame on Windows (re-edited)

crates/eframe/src/native/glow_integration.rs

@@ -1284,7 +1284,6 @@ impl GlutinWindowContext {
             if let Some(window) = &viewport.window {
                 let old_inner_size = window.inner_size();
 
-                let is_viewport_focused = self.focused_viewport == Some(viewport_id);
                 viewport.deferred_commands.append(&mut commands);
 
                 egui_winit::process_viewport_commands(
@@ -1292,7 +1291,6 @@ impl GlutinWindowContext {
                     &mut viewport.info,
                     std::mem::take(&mut viewport.deferred_commands),
                     window,
-                    is_viewport_focused,
                     &mut viewport.actions_requested,
                 );
 

crates/eframe/src/native/wgpu_integration.rs

@@ -635,7 +635,7 @@ impl WgpuWinitRunning {
             viewports,
             painter,
             viewport_from_window,
-            focused_viewport,
+            ..
         } = &mut *shared_mut;
 
         let FullOutput {
@@ -724,7 +724,6 @@ impl WgpuWinitRunning {
             viewports,
             painter,
             viewport_from_window,
-            *focused_viewport,
         );
 
         // Prune dead viewports:
@@ -996,7 +995,6 @@ fn render_immediate_viewport(
         viewports,
         painter,
         viewport_from_window,
-        focused_viewport,
         ..
     } = &mut *shared_mut;
 
@@ -1036,7 +1034,6 @@ fn render_immediate_viewport(
         viewports,
         painter,
         viewport_from_window,
-        *focused_viewport,
     );
 }
 
@@ -1061,7 +1058,6 @@ fn handle_viewport_output(
     viewports: &mut ViewportIdMap<Viewport>,
     painter: &mut egui_wgpu::winit::Painter,
     viewport_from_window: &mut HashMap<WindowId, ViewportId>,
-    focused_viewport: Option<ViewportId>,
 ) {
     for (
         viewport_id,
@@ -1083,7 +1079,6 @@ fn handle_viewport_output(
         if let Some(window) = viewport.window.as_ref() {
             let old_inner_size = window.inner_size();
 
-            let is_viewport_focused = focused_viewport == Some(viewport_id);
             viewport.deferred_commands.append(&mut commands);
 
             egui_winit::process_viewport_commands(
@@ -1091,7 +1086,6 @@ fn handle_viewport_output(
                 &mut viewport.info,
                 std::mem::take(&mut viewport.deferred_commands),
                 window,
-                is_viewport_focused,
                 &mut viewport.actions_requested,
             );
 

crates/egui-winit/src/lib.rs

@@ -1284,18 +1284,10 @@ pub fn process_viewport_commands(
     info: &mut ViewportInfo,
     commands: impl IntoIterator<Item = ViewportCommand>,
     window: &Window,
-    is_viewport_focused: bool,
     actions_requested: &mut HashSet<ActionRequested>,
 ) {
     for command in commands {
-        process_viewport_command(
+        process_viewport_command(egui_ctx, window, command, info, actions_requested);
-            egui_ctx,
-            window,
-            command,
-            info,
-            is_viewport_focused,
-            actions_requested,
-        );
     }
 }
 
@@ -1304,7 +1296,6 @@ fn process_viewport_command(
     window: &Window,
     command: ViewportCommand,
     info: &mut ViewportInfo,
-    is_viewport_focused: bool,
     actions_requested: &mut HashSet<ActionRequested>,
 ) {
     crate::profile_function!();
@@ -1323,12 +1314,8 @@ fn process_viewport_command(
             // Need to be handled elsewhere
         }
         ViewportCommand::StartDrag => {
-            // If `is_viewport_focused` is not checked on x11 the input will be permanently taken until the app is killed!
+            // If `.has_focus()` is not checked on x11 the input will be permanently taken until the app is killed!
-
+            if window.has_focus() {
-            // TODO(emilk): check that the left mouse-button was pressed down recently,
-            // or we will have bugs on Windows.
-            // See https://github.com/emilk/egui/pull/1108
-            if is_viewport_focused {
                 if let Err(err) = window.drag_window() {
                     log::warn!("{command:?}: {err}");
                 }

crates/egui_glow/src/winit.rs

@@ -85,7 +85,6 @@ impl EguiGlow {
                 &mut self.viewport_info,
                 commands,
                 window,
-                true,
                 &mut actions_requested,
             );
             for action in actions_requested {

examples/custom_window_frame/src/main.rs

@@ -112,7 +112,7 @@ fn title_bar_ui(ui: &mut egui::Ui, title_bar_rect: eframe::epaint::Rect, title:
             .send_viewport_cmd(ViewportCommand::Maximized(!is_maximized));
     }
 
-    if title_bar_response.dragged_by(PointerButton::Primary) {
+    if title_bar_response.drag_started_by(PointerButton::Primary) {
         ui.ctx().send_viewport_cmd(ViewportCommand::StartDrag);
     }