feat(v3): MessageDialog.Show() returns clicked button label

Make MessageDialog.Show() return the clicked button's label as a string,
enabling synchronous dialog workflows. This allows developers to use
switch statements on the result instead of callbacks for decision-making
flows.

All platforms now consistently block until the user clicks a button and
return the label. Button callbacks are still called for backwards
compatibility.

Closes #4792

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: leaanthony

v3/UNRELEASED_CHANGELOG.md

@@ -20,6 +20,7 @@ After processing, the content will be moved to the main changelog and this file
 
 ## Changed
 <!-- Changes in existing functionality -->
+- `MessageDialog.Show()` now returns the clicked button's label as a string, enabling synchronous dialog workflows (#4792)
 
 ## Fixed
 <!-- Bug fixes -->

v3/pkg/application/dialogs.go

@@ -66,7 +66,7 @@ func (b *Button) SetAsCancel() *Button {
 }
 
 type messageDialogImpl interface {
-	show()
+	show() string
 }
 
 type MessageDialogOptions struct {
@@ -106,11 +106,14 @@ func (d *MessageDialog) SetTitle(title string) *MessageDialog {
 	return d
 }
 
-func (d *MessageDialog) Show() {
+// Show displays the dialog and returns the label of the clicked button.
+// This method blocks until the user clicks a button.
+// If the dialog has button callbacks defined, they will still be called.
+func (d *MessageDialog) Show() string {
 	if d.impl == nil {
 		d.impl = newDialogImpl(d)
 	}
-	InvokeSync(d.impl.show)
+	return InvokeSyncWithResult(d.impl.show)
 }
 
 func (d *MessageDialog) SetIcon(icon []byte) *MessageDialog {

v3/pkg/application/dialogs_android.go

@@ -65,8 +65,9 @@ type androidDialog struct {
 	dialog *MessageDialog
 }
 
-func (d *androidDialog) show() {
+func (d *androidDialog) show() string {
 	// TODO: Implement using AlertDialog
+	return ""
 }
 
 func newDialogImpl(d *MessageDialog) *androidDialog {

v3/pkg/application/dialogs_darwin.go

@@ -371,7 +371,10 @@ type macosDialog struct {
 	nsDialog unsafe.Pointer
 }
 
-func (m *macosDialog) show() {
+func (m *macosDialog) show() string {
+	// Channel to receive the result
+	resultChan := make(chan string, 1)
+
 	InvokeAsync(func() {
 
 		// Mac can only have 4 Buttons on a dialog
@@ -429,19 +432,24 @@ func (m *macosDialog) show() {
 
 		var callBackID int
 		callBackID = addDialogCallback(func(buttonPressed int) {
+			var buttonLabel string
 			if len(m.dialog.Buttons) > buttonPressed {
 				button := reversedButtons[buttonPressed]
+				buttonLabel = button.Label
 				if button.Callback != nil {
 					button.Callback()
 				}
 			}
 			removeDialogCallback(callBackID)
+			resultChan <- buttonLabel
 		})
 
 		C.dialogRunModal(m.nsDialog, parent, C.int(callBackID))
 
 	})
 
+	// Wait for and return the result
+	return <-resultChan
 }
 
 func newDialogImpl(d *MessageDialog) *macosDialog {

v3/pkg/application/dialogs_ios.go

@@ -65,8 +65,9 @@ type iosDialog struct {
 	dialog *MessageDialog
 }
 
-func (d *iosDialog) show() {
+func (d *iosDialog) show() string {
 	// TODO: Implement using UIAlertController
+	return ""
 }
 
 func newDialogImpl(d *MessageDialog) *iosDialog {
@@ -87,4 +88,4 @@ func newOpenFileDialogImpl(_ *OpenFileDialogStruct) openFileDialogImpl {
 
 func newSaveFileDialogImpl(_ *SaveFileDialogStruct) saveFileDialogImpl {
 	return &dialogsImpl{}
-}
+}

v3/pkg/application/dialogs_linux.go

@@ -27,7 +27,7 @@ type linuxDialog struct {
 	dialog *MessageDialog
 }
 
-func (m *linuxDialog) show() {
+func (m *linuxDialog) show() string {
 	windowId := getNativeApplication().getCurrentWindowID()
 	window, _ := globalApplication.Window.GetByID(windowId)
 	var parent uintptr
@@ -38,18 +38,27 @@ func (m *linuxDialog) show() {
 		}
 	}
 
+	// Channel to receive the result
+	resultChan := make(chan string, 1)
+
 	InvokeAsync(func() {
 		response := runQuestionDialog(pointer(parent), m.dialog)
+		var buttonLabel string
 		if response >= 0 && response < len(m.dialog.Buttons) {
 			button := m.dialog.Buttons[response]
+			buttonLabel = button.Label
 			if button.Callback != nil {
 				go func() {
 					defer handlePanic()
 					button.Callback()
 				}()
 			}
 		}
+		resultChan <- buttonLabel
 	})
+
+	// Wait for and return the result
+	return <-resultChan
 }
 
 func newDialogImpl(d *MessageDialog) *linuxDialog {

v3/pkg/application/dialogs_windows.go

@@ -30,7 +30,7 @@ type windowsDialog struct {
 	UseAppIcon bool
 }
 
-func (m *windowsDialog) show() {
+func (m *windowsDialog) show() string {
 
 	title := w32.MustStringToUTF16Ptr(m.dialog.Title)
 	message := w32.MustStringToUTF16Ptr(m.dialog.Message)
@@ -72,6 +72,7 @@ func (m *windowsDialog) show() {
 			}
 		}
 	}
+	return result
 }
 
 func newDialogImpl(d *MessageDialog) *windowsDialog {