Unfortunately, no. Because it is a dialog window and not just a window (a clear distinction in the framework in which the software runs), it doesn't have the standard Windows minimize/maximize/restore buttons.
But, I did build in key combinations to maximize and restore the dialog's size. Press Ctrl+Alt+Shift+F for "full size" and Ctrl+Alt+Shift+O for "original size". These are hotkeys in the final version of 2.6, so you can assign your own key combinations.