EXT-803 Parcel highlight stays lit after setting a parcel for sale and closing...

EXT-803 Parcel highlight stays lit after setting a parcel for sale and closing the About Land floater.  The LLFloaterReg conversion made this floater single_instance, which means it does not destroy itself on close.  We therefore need to explicitly clean up the parcel selection when the sell land floater is closed.  Reviewed with Leyla.

indra/newview/llfloatersellland.cpp

@@ -58,6 +58,7 @@ class LLFloaterSellLandUI
 public:
 	LLFloaterSellLandUI(const LLSD& key);
 	virtual ~LLFloaterSellLandUI();
+	void onClose();
 	
 private:
 	class SelectionObserver : public LLParcelObserver
@@ -131,6 +132,7 @@ LLFloaterSellLandUI::LLFloaterSellLandUI(const LLSD& key)
 {
 	LLViewerParcelMgr::getInstance()->addObserver(&mParcelSelectionObserver);
 // 	LLUICtrlFactory::getInstance()->buildFloater(sInstance, "floater_sell_land.xml");
+	mCloseSignal.connect(boost::bind(&LLFloaterSellLandUI::onClose, this));
 }
 
 LLFloaterSellLandUI::~LLFloaterSellLandUI()
@@ -138,6 +140,13 @@ LLFloaterSellLandUI::~LLFloaterSellLandUI()
 	LLViewerParcelMgr::getInstance()->removeObserver(&mParcelSelectionObserver);
 }
 
+// Because we are single_instance, we are not destroyed on close.
+void LLFloaterSellLandUI::onClose()
+{
+	// Must release parcel selection to allow land to deselect, see EXT-803
+	mParcelSelection = NULL;
+}
+
 void LLFloaterSellLandUI::SelectionObserver::changed()
 {
 	if (LLViewerParcelMgr::getInstance()->selectionEmpty())
@@ -253,10 +262,7 @@ void LLFloaterSellLandUI::refreshUI()
 	if (!parcelp) return;
 
 	LLTextureCtrl* snapshot = getChild<LLTextureCtrl>("info_image");
-	if (snapshot)
-	{
-		snapshot->setImageAssetID(mParcelSnapshot);
-	}
+	snapshot->setImageAssetID(mParcelSnapshot);
 
 	childSetText("info_parcel", parcelp->getName());
 	childSetTextArg("info_size", "[AREA]", llformat("%d", mParcelActualArea));