Command- Spacebar is a shortcut to select the last tool used.
If Command- Spacebar does not function, check to see if SCSI Probe is installed. SCSI Probe 3.0 is preset to use Command-Spacebar to mount volumes. To fix this, select SCSI Probe in the Control Panel, click the Options button, then type a different keyboard command. The new key combination you type will replace the Command-Spacebar option.
Now if you try the Command- Spacebar in MacDraw Pro, it will behave as expected.