Desktop: Text clipboard support (#3461)

* gray background for viewport texture

* cust copy paste support

* connect clipboard read on web

* fix eyedropper bounds

* cleanup

* add missing char events for some named keys like enter

desktop/wrapper/src/messages.rs

@@ -54,6 +54,10 @@ pub enum DesktopFrontendMessage {
 	UpdateMenu {
 		entries: Vec<MenuItem>,
 	},
+	ClipboardRead,
+	ClipboardWrite {
+		content: String,
+	},
 	WindowClose,
 	WindowMinimize,
 	WindowMaximize,
@@ -114,6 +118,9 @@ pub enum DesktopWrapperMessage {
 	MenuEvent {
 		id: String,
 	},
+	ClipboardReadResult {
+		content: Option<String>,
+	},
 }
 
 #[derive(Clone, serde::Serialize, serde::Deserialize, Debug)]