bugfix: Refresh RTG panel when CPU changes are modified

- The 24-bit addressing option blocks RTG cards from being used. When it's disabled, the RTG panel should refresh, to enable any relevant widgets
- Fixed navigation in RTG panel (the VRAM slider could not be accessed)

src/osdep/gui/PanelCPU.cpp

@@ -93,6 +93,7 @@ class CPUButtonActionListener : public gcn::ActionListener
 		RefreshPanelCPU();
 		RefreshPanelRAM();
 		RefreshPanelChipset();
+		RefreshPanelRTG();
 	}
 };
 

src/osdep/gui/PanelRTG.cpp

@@ -190,7 +190,7 @@ void InitPanelRTG(const config_category& category)
 	sldGfxmem->setForegroundColor(gui_foreground_color);
 	sldGfxmem->setMarkerLength(marker_length);
 	sldGfxmem->setStepLength(1);
-	sldGfxmem->setId("Gfxmem");
+	sldGfxmem->setId("sldGfxmem");
 	sldGfxmem->addActionListener(rtg_action_listener);
 
 	chkRtgMatchDepth = new gcn::CheckBox("Match host and RTG color depth if possible");