I play with a gamepad/chatpad and love it. There are only 2 things that make me reach for the mouse and its anoying when im playing on the big screen on my couch. Wanted to give a suggestion about fixing this.
First, you cannot go to the chat window with the gamepad.
To fix this i suggest to use the button assigned (Y button on the 360 controller) to [target status effect window] to toggle between the [target status effect window] and the [chat window]. Once you get to chat window you can switch tabs by using the trigger buttons and hit the confirm button to get into a chat tab, then u can scroll up and down with the "target/menu navigation" cross. Exit out with the cancel button. (took this idea from ffxi, where i never needed the mouse)

The second thing you can't open with the pad is the [Use Item window].
For this i suggest to use the the same button (Y) while holding the autorun button.