The command stack stores up to three commands and is visible at the bottom, left-hand corner of the application window:
The stack is altered when you choose a new command, cancel a command, or a command is completed. The stack follows this set of rules:
The bottom command on the stack is always the Default command; you cannot remove it from the stack.
The second command on the stack can be any Structure or camera command.
The third command can only be a camera command; if a new Structure command is chosen while three commands are on the stack, the third and second commands are removed from the stack and the new command is pushed onto the stack in second place. If a new camera command is chosen while three commands are on the stack, it replaces the third command.
You can remove a command from the stack by pressing the Esc key, or on the Structure view toolbar clicking the button, or by right-clicking and choosing from the context menu. These actions undo any incomplete changes from the current command.
You can finish or move on to the next step in the current command by pressing the Enter key, or on the Structure view toolbar clicking the button , or by right-clicking and choosing from the context menu.
If the topmost command is a Structure command, it displays special instructions in yellow at the bottom of the application window. These instructions explain the next operation the command expects, such as placing a corner of a box. It may also convey additional information regarding actions that you can take at any time, like pressing the Esc key to cancel the command.
Example: The command stack begins with only the default command. If you choose a camera command, for example, a rotate command, it is pushed onto the second place in the stack. If you choose another camera command such as zoom, it is pushed onto the third place in the stack. If you choose a structure command such as draw box, the third camera command in the stack, Zoom, is removed and the second command in the stack, Rotate, is replaced with Draw Box.
If you choose a camera command such as spin, it is added to the third place in the command stack . If you cancel, the camera command in the third place is removed. If you cancel again, the command stack is left with the default command.