Improve settings button selection handling

Will now try to keep the current button selection if possible.
This can be useful when switching between source of the same time.

plugins/base/macro-action-source.hpp

@@ -80,7 +80,7 @@ public:
 private slots:
 	void SourceChanged(const SourceSelection &);
 	void ActionChanged(int value);
-	void ButtonChanged(int idx);
+	void ButtonChanged(const SourceSettingButton &);
 	void GetSettingsClicked();
 	void SettingsStringChanged();
 	void DeinterlaceModeChanged(int);
@@ -99,7 +99,7 @@ private:
 
 	SourceSelectionWidget *_sources;
 	QComboBox *_actions;
-	QComboBox *_settingsButtons;
+	SourceSettingsButtonSelection *_settingsButtons;
 	QHBoxLayout *_settingsLayout;
 	QComboBox *_settingsInputMethods;
 	VariableTextEdit *_manualSettingValue;