Dev-PHP is a well-featured IDE for PHP. Fast and powerful, it is easy to use and has a lot of cool features : class browser, scripts preview, integration with PHP parsers, PHP-GTK library, and Xdebug of course. Dev-PHP-usb slips even into your pocket.
Initial impression is this software is full of bugs. Drag and drop a PHP file to it, it throws an error. The PHP file is opened but not displayed. You cannot dismiss pop-out tool panels without closing them, as there is nothing to take focus away. After these failures, I simply uninstalled it. Granted, getting further into the editor may provide a less buggy experience, but because the PHP file wasn't even displayed, I couldn't do anything.