How do I turn off mouse block selection in IntelliJ?

For some reason, dragging the mouse cursor started doing block selects instead of the normal line select mode: ![enter image description here][1] (Please ignore the fact that this image is from Visual Studio and not IntelliJ) I tried pressing scroll-lock, pressing and releasing the alt/ctrl/shift keys, but still selecting doesn't revert to the normal "select full lines" mode. When I click and hold, then drag the mouse, I get a block (rectangle) selection. Do you know how to undo this? P.S. I'm running IntelliJ 9 on Ubuntu. P.S. Holding SHIFT and pressing the up arrow button also does block select instead of normal multiline select. [1]: https://i.sstatic.net/70bmw.png