Hide PiP hide button unless mouse is over PiP window

src/QmlControls/QGCPipable.qml

@@ -124,7 +124,7 @@ Item {
         fillMode:       Image.PreserveAspectFit
         anchors.left:   parent.left
         anchors.bottom: parent.bottom
-        visible:        !isHidden
+        visible:        !isHidden && pipMouseArea.containsMouse
         height:         ScreenTools.defaultFontPixelHeight * 2.5
         width:          ScreenTools.defaultFontPixelHeight * 2.5
         sourceSize.height:  height