EXT-7000 FIX "eat" TAB key while menu is active

Two problems:
1. AvatarList didn't hide popup menu when goes invisible.
2. (Real problem) MenuHolder View didn't process TAB key. Which leads to changing active ("focused") control. Which leads to the ability (for example) to switch tabs and hide popup menu parent view.

--HG--
branch : product-engine

indra/llui/llmenugl.cpp

@@ -3420,6 +3420,12 @@ BOOL LLMenuHolderGL::handleKey(KEY key, MASK mask, BOOL called_from_parent)
 			
 	if (pMenu)
 	{
+		//eat TAB key - EXT-7000
+		if (key == KEY_TAB && mask == MASK_NONE)
+		{
+			return TRUE;
+		}
+
 		//handle ESCAPE and RETURN key
 		handled = LLPanel::handleKey(key, mask, called_from_parent);
 		if (!handled)

indra/newview/llavatarlist.cpp

@@ -399,6 +399,15 @@ BOOL LLAvatarList::handleRightMouseDown(S32 x, S32 y, MASK mask)
 	return handled;
 }
 
+void LLAvatarList::setVisible(BOOL visible)
+{
+	if ( visible == FALSE && mContextMenu )
+	{
+		mContextMenu->hide();
+	}
+	LLFlatListViewEx::setVisible(visible);
+}
+
 void LLAvatarList::computeDifference(
 	const uuid_vec_t& vnew_unsorted,
 	uuid_vec_t& vadded,

indra/newview/llavatarlist.h

@@ -70,6 +70,8 @@ public:
 
 	virtual void clear();
 
+	virtual void setVisible(BOOL visible);
+
 	void setNameFilter(const std::string& filter);
 	void setDirty(bool val = true, bool force_refresh = false);
 	uuid_vec_t& getIDs() 							{ return mIDs; }

indra/newview/llavatarlistitem.h

@@ -71,6 +71,7 @@ public:
 	{
 	public:
 		virtual void show(LLView* spawning_view, const uuid_vec_t& selected_uuids, S32 x, S32 y) = 0;
+		virtual void hide() = 0;
 	};
 
 	/**