Prevent VisualShader Editor Add/Remove popups from accidentally being…

… hidden

VisualShader Editor windows, such as `Create Shader Node`, `Create Shader Varying` and `Delete Shader Varying` open up as dedicated windows and can end up hidden behind the Godot editor if a user clicks more than once when opening these dialogues. A user's natural reaction is to assume the dialogue closed and try to open it again, but nothing will happen when they try to do so, since an open instance actually still exists, which they would have to notice on their task bar for example (which looks just like another Godot instance), otherwise, they will assume there is a bug. It's isn't the best UX.

I propose making these 3 menus "exclusive", since you shouldn't really be trying to do other stuff during them anyways, and this will avoid them accidentally disappearing and confusing users.

editor/plugins/visual_shader_editor_plugin.cpp

@@ -5485,7 +5485,7 @@ VisualShaderEditor::VisualShaderEditor() {
 
 	members_dialog = memnew(ConfirmationDialog);
 	members_dialog->set_title(TTR("Create Shader Node"));
-	members_dialog->set_exclusive(false);
+	members_dialog->set_exclusive(true);
 	members_dialog->add_child(members_vb);
 	members_dialog->set_ok_button_text(TTR("Create"));
 	members_dialog->get_ok_button()->connect("pressed", callable_mp(this, &VisualShaderEditor::_member_create));
@@ -5497,7 +5497,7 @@ VisualShaderEditor::VisualShaderEditor() {
 	{
 		add_varying_dialog = memnew(ConfirmationDialog);
 		add_varying_dialog->set_title(TTR("Create Shader Varying"));
-		add_varying_dialog->set_exclusive(false);
+		add_varying_dialog->set_exclusive(true);
 		add_varying_dialog->set_ok_button_text(TTR("Create"));
 		add_varying_dialog->get_ok_button()->connect("pressed", callable_mp(this, &VisualShaderEditor::_varying_create));
 		add_varying_dialog->get_ok_button()->set_disabled(true);
@@ -5543,7 +5543,7 @@ VisualShaderEditor::VisualShaderEditor() {
 	{
 		remove_varying_dialog = memnew(ConfirmationDialog);
 		remove_varying_dialog->set_title(TTR("Delete Shader Varying"));
-		remove_varying_dialog->set_exclusive(false);
+		remove_varying_dialog->set_exclusive(true);
 		remove_varying_dialog->set_ok_button_text(TTR("Delete"));
 		remove_varying_dialog->get_ok_button()->connect("pressed", callable_mp(this, &VisualShaderEditor::_varying_deleted));
 		add_child(remove_varying_dialog);