I'm activating the measure tool through code by using the ControlsMapMeasureToolClass. I want programmmatically to change the default length units of tool. How do do that?
Built-in commands and windows are generally black boxes that have predefined behaviors and little to no exposed settings.
The built-in Measure Tool appears to use the active data frame's coordinate system to determine which units to display by default. You can of course interactively change the displayed units by clicking the first small black arrow on the Measure tool window:
What you could try is changing the focused map's