It's an issue others have complained about. Temporarily changing the fill color is one option for moving the object. Other options are to drag to select it and use the arrow keys or the position/alignment tools on the Inspector's position tab to move the object to where you want it.
But one caveat about using the Inspector to reposition an object. Some layout objects, tab controls, sliders, popovers, portals, need to "own" the object in order for that object to display and function correctly as part of that enclosing object. You can tell if one of these enclosing objects "owns" an object because if you move the portal or other enclosing object, the "owned" objects move with it. If you use the inspector to move an object from outside the enclosing object to within its boundaries, the object is positioned on top of the enclosing object, it is not "owned" by the object.