The marked area (sometimes called “selection” in other applications) is now more flexible than before, and it is persistent as long as the image isn’t resized. Also, if you change the marked area after opening a tool that refers to it, you can now update the coordinates. If you press shift during marking, the marked area will be a square. If you press ctrl, the marking will not “snap” to the image edges.
The text annotation tool is now more powerful… the rest is up to you to discover!