Fixed EXT-4646 ([BSI] Movement controls close after hitting stand)

- reason: fix for bug EXT-2504 (black bars present at top and bottom when in mouselook) (changing parent visibility of panel with "Stand/Stop flying" buttons)
- fix: updated condition to process visibility of the parent of the panel with "Stand/Stop flying" buttons: only if panel is not attached to Move Floater
	NOTE: The same problem was for EXT-3632 (Move floater closes after user click on Stop Flying btn)
	Reverted that fix for Stop flying button to be consistent with "Stand".

--HG--
branch : product-engine

indra/newview/llmoveview.cpp

@@ -589,9 +589,13 @@ void LLPanelStandStopFlying::setVisible(BOOL visible)
 		updatePosition();
 	}
 
-	//change visibility of parent layout_panel to animate in/out
+	// do not change parent visibility in case panel is attached into Move Floater: EXT-3632, EXT-4646
+	if (!mAttached) 
+	{
+		//change visibility of parent layout_panel to animate in/out. EXT-2504
 		if (getParent()) getParent()->setVisible(visible);
 	}
+}
 
 BOOL LLPanelStandStopFlying::handleToolTip(S32 x, S32 y, MASK mask)
 {
@@ -614,7 +618,7 @@ void LLPanelStandStopFlying::reparent(LLFloaterMove* move_view)
 	LLPanel* parent = dynamic_cast<LLPanel*>(getParent());
 	if (!parent)
 	{
-		llwarns << "Stand/stop flying panel parent is unset" << llendl;
+		llwarns << "Stand/stop flying panel parent is unset, already attached?: " << mAttached << ", new parent: " << (move_view == NULL ? "NULL" : "Move Floater") << llendl;
 		return;
 	}
 
@@ -684,6 +688,7 @@ void LLPanelStandStopFlying::onStopFlyingButtonClick()
 	gAgent.setFlying(FALSE);
 
 	setFocus(FALSE); // EXT-482
+	setVisible(FALSE);
 }
 
 /**