Prevent the arrow toggles from stealing focus from the canvas

This can cause confusing behaviour by consuming hotkeys such as Enter that are intended to be used for finalizing the shape tools.

Fixes: #2092414

Pinta.Tools/Editable/EditEngines/ArrowedEditEngine.cs

@@ -273,6 +273,7 @@ private Gtk.CheckButton ArrowOneEnabledCheckBox
 	private Gtk.CheckButton CreateArrowOneEnabledCheckBox ()
 	{
 		Gtk.CheckButton result = Gtk.CheckButton.NewWithLabel ("1");
+		result.FocusOnClick = false;
 		result.Active = settings.GetSetting (ARROW1_SETTING (tool_prefix), previous_settings_1.Show);
 		result.OnToggled += (o, e) => ArrowEnabledToggled (true);
 		return result;
@@ -284,6 +285,7 @@ private Gtk.CheckButton ArrowTwoEnabledCheckBox
 	private Gtk.CheckButton CreateArrowTwoEnabledCheckBox ()
 	{
 		Gtk.CheckButton result = Gtk.CheckButton.NewWithLabel ("2");
+		result.FocusOnClick = false;
 		result.Active = settings.GetSetting (ARROW2_SETTING (tool_prefix), previous_settings_2.Show);
 		result.OnToggled += (o, e) => ArrowEnabledToggled (false);
 		return result;