In the Source Editor in the IDE, you often need to select a single line, for copying or whatever. There's a keyboard shortcut you can set for that, in the Keymap's "Other" section, you can set the "Select Line" shortcut to something. However, there's no need to do that. Why? Because you can select a line like this:
And... now the whole line is selected. The split second pause is important, as is getting the timing right. (And sometimes the split second isn't even necessary, just click three times.) But, once you've got it, it saves a lot of time. Now you can do Ctrl-C (or anything else applicable to a line) to work with the line. You can also right click and then choose a line-related action from the contextual menu.