Ahh OK, no not seen that. You could still use a popup with the template and calculate the size required. But if the drop points are user defined, You may not be able to read them from the OS.
And the thing that is missing from the Titlebar is selecting the other windows to reposition. For example when the window is dropped in a 'half screen' position Windows allows you to choose another window to fill the other half.
Theoretically you could use the JNA to get a list of all of the windows and allow selection of the windows to position as appropriate, but is it really worth it?