Add some initial widget functionality (prefs partly working)

PortabilityLayer/PLButtonWidget.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "PascalStr.h"
+#include "PLWidgets.h"
+
+namespace PortabilityLayer
+{
+	class ButtonWidget final : public WidgetSpec<ButtonWidget>
+	{
+	public:
+		explicit ButtonWidget(const WidgetBasicState &state);
+
+		bool Init(const WidgetBasicState &state) override;
+
+		WidgetHandleState_t ProcessEvent(Window *window, const TimeTaggedVOSEvent &evt);
+
+	private:
+		bool m_haveMouseDown;
+		PascalStr<255> m_text;
+	};
+}