Save yourself from disaster by stopping in the middle of a command with the Escape key:
We already know the Escape key can be used to 'unselect' something in both 2D and 3D. It works the same as the Selection Tool icon on your tool bar.
However, the Escape key can also be used to 'unselect' an item when you are in the middle of a command. Here are some examples:
When drawing a new I-line:
1.Click and drag an I-line (but don't let go yet!).
2.Change your mind? Wrong location? Wrong Style? Just press the Escape key.
When editing an existing I-line:
1.Tried to select the horizontal I-line but got the vertical one instead?
2.Before letting go press ESC and the I-line will get unselected and return to it's original location.
When moving items:
1.Box select two cabinets to move. You accidentally selected the nearby I-line as well.
2.Before letting go, press ESC and all the selected items will return to their original location.
1.ESC will halt all of these commands mid-stream.
2.Before completing the command, if that action is NOT what you want to do, press ESC and the command will stop.
NOTE: Right-clicking the mouse in the middle of a command does the same thing as the Escape key. But it can be tricky since you are already holding down the left mouse button at the same time. The Escape key is easier and gives your other hand something to do.