Aligned Dimension

[twallVCXPH]

I need to put a diagonal dimension across a Life Safety Floor Plan.  Corner to corner.  No leader lines just arrows at both ends pointing to the corner.  The "aligned dimension" command won't start at the point I want it keeps selecting the walls. 

How do I do this? 

[mhiserZFHXS]

Put your mouse at your start corner and hit tab until just a dot is highlighted, click, and then do the same for the next corner.

[wisedrawing]

This took me a while to get too, when you first do the tabbing through various highlighted snapping options you think its strange (Coming of ACAD the king of snapping). In some circumstances there are a lot of options to toggle through so it seems it might never happen. Sometimes Revit will not bring up the dot if there is nothing suitable to click to (rare) but its possible that is your issue if the item does not support a click. Even a masked region with lines will allow it. if it does not support then maybe lock snap a detail line and snap to that?

Linear works by orthographic squaring it up and aligned is the one you want.

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