Windows: Fix dragging sometimes not showing indicators

DragController thought there was a resize going on.
The hardcoded margins in FloatingWindow::isInDragArea() arent
needed anymore.

iPlease enter the commit message for your changes. Lines starting

src/private/FloatingWindow.cpp

@@ -270,7 +270,7 @@ MultiSplitter *FloatingWindow::multiSplitter() const
 
 bool FloatingWindow::isInDragArea(QPoint globalPoint) const
 {
-    return dragRect().adjusted(8, 8, 0, 0).contains(globalPoint);
+    return dragRect().contains(globalPoint);
 }
 
 bool FloatingWindow::anyNonClosable() const