eframe: Mouse passthrough option (#2080)

crates/eframe/src/epi.rs

@@ -270,6 +270,10 @@ pub struct NativeOptions {
     /// You should avoid having a [`egui::CentralPanel`], or make sure its frame is also transparent.
     pub transparent: bool,
 
+    /// On desktop: mouse clicks pass through the window, used for non-interactable overlays
+    /// Generally you would use this in conjunction with always_on_top
+    pub mouse_passthrough: bool,
+
     /// Turn on vertical syncing, limiting the FPS to the display refresh rate.
     ///
     /// The default is `true`.
@@ -389,6 +393,7 @@ impl Default for NativeOptions {
             max_window_size: None,
             resizable: true,
             transparent: false,
+            mouse_passthrough: false,
             vsync: true,
             multisampling: 0,
             depth_buffer: 0,