On my netbook with 1024×600 resolution, SmartSVN did not allow me to maximize it’s main window. It was just to big to fit the screen. I thought it was caused by width of toolbar buttons, so I removed some of them from toolbar. Unfortunately it did not help.
After some diging on the Internet, I found documentation page on SmartSVN site with description of VM options.
Among other cool options, there is a possibility to remove text from the toolbar buttons using smartsvn.toolbar.textBelowIcon configuration option. By setting this option to false in the ~/.smartsvn/6.6/smartsvn.properties file, I was able to maximize the window correctly.