Here is a Link to the Maxthon Forums.http://forum.maxthon.com/forum/index.php
I did a search for "Maximize window"http://forum.maxthon.com/forum/index.php?act=Search&CODE=show&searchid=772a402cacb2294af67540b2caf27166&search_in=posts&result_type=topics&highlite=maximized
There seems to be enough info there to fix your problem.
PS I have been using Maxthon with WB for a long time with minimal problems. Good luck, let us know how it is going.
EDIT--This might help. Disable the 'Show popups in sized tabs' option (Options >> Maxthon Options >> Popups).