Track the global focus state of the UI (#1859)

* Track the global focus state of the UI

* Fix changelog entries

* Document the new difference between `Response::has_focus` and `Memory::has_focus`

egui-winit/CHANGELOG.md

@@ -8,6 +8,7 @@ All notable changes to the `egui-winit` integration will be noted in this file.
 * Allow deferred render + surface state initialization for Android ([#1634](https://github.com/emilk/egui/pull/1634)).
 * Fixed window position persistence ([#1745](https://github.com/emilk/egui/pull/1745)).
 * Fixed mouse cursor change on Linux ([#1747](https://github.com/emilk/egui/pull/1747)).
+* Use the new `RawInput::has_focus` field to indicate whether the window has the keyboard focus ([#1859](https://github.com/emilk/egui/pull/1859)).
 
 
 ## 0.18.0 - 2022-04-30

egui-winit/src/lib.rs

@@ -70,9 +70,14 @@ impl State {
     }
 
     pub fn new_with_wayland_display(wayland_display: Option<*mut c_void>) -> Self {
+        let egui_input = egui::RawInput {
+            has_focus: false, // winit will tell us when we have focus
+            ..Default::default()
+        };
+
         Self {
             start_time: instant::Instant::now(),
-            egui_input: Default::default(),
+            egui_input,
             pointer_pos_in_points: None,
             any_pointer_button_down: false,
             current_cursor_icon: egui::CursorIcon::Default,
@@ -214,7 +219,8 @@ impl State {
                 egui_ctx.wants_keyboard_input()
                     || input.virtual_keycode == Some(winit::event::VirtualKeyCode::Tab)
             }
-            WindowEvent::Focused(_) => {
+            WindowEvent::Focused(has_focus) => {
+                self.egui_input.has_focus = *has_focus;
                 // We will not be given a KeyboardInput event when the modifiers are released while
                 // the window does not have focus. Unset all modifier state to be safe.
                 self.egui_input.modifiers = egui::Modifiers::default();