Photoshop: Warp - things you did not know

If you know what Warp is, you probably know how to access it. In case you don't it is in the menu Edit > Transform > Warp.

Using Warp, you can drag about any point of the warped object. You do not have to click-drag on the corner points or lines. You can click-drag on the vast empty spaces between the lines as well.

If you end up with a Warp grid that goes outside the current window, press command-0 (View > Fit on Screen) to see the entire grid.