Fedora :: Inhibit Transmission While User Active?

Is there a way to inhibit Transmission at times when a user is active and only have it downloading/seeding when the computer is idle (or is there another Torrent client that will do so)? I know about the limits that can be set, but those are clock based, not activity based limitations. As it is now, when it is running, my web browsing speed and other online activities take a big hit in responsiveness. I want to be responsible and seed completed downloads. However, the performance hit makes it difficult to tolerate, and manually pausing and resuming torrents every time I sit down at the computer or get up to leave is inconvenient.