handle click dock icon to reopen app for Mac

ui/app_delegate_darwin.go

@@ -0,0 +1,27 @@
+//go:build darwin
+
+package ui
+
+/*
+void installReopenDelegate();
+*/
+import "C"
+
+import "fyne.io/fyne/v2"
+
+var darwinAppDelegateReopenWindow fyne.Window
+
+func installReopenHandler(w fyne.Window) {
+	darwinAppDelegateReopenWindow = w
+	C.installReopenDelegate()
+}
+
+//export appReopened
+func appReopened() {
+	if darwinAppDelegateReopenWindow == nil {
+		return
+	}
+	go func() {
+		fyne.Do(darwinAppDelegateReopenWindow.Show)
+	}()
+}