One small complaint I have with Solidworks Sketching has to do with the Smart Dimension tool.  

Here is an example.  

Say I sketch out a rectangle with Sides A and B.  No dimensions are set.  I open dimension tool and click side A which is let's say 9" before dimensioning and give it a dimension of 8".  Then I click side B which pops up the smart dimension box and it shows 3".  Then I decide I don't want to give it a dimension after all.  If I have clicked to open the dimension dialogue box even hitting escape or red X does not cancel dimension.  It simply places the current value as a dimension in this case 3".  Then if I hit UNDO, it will delete dimension but ALSO reverts my 8" dimension back to 9" also!  

This is a real annoyance if I click on a line by mistake.  Then I have to go back and delete the dimension first before dimensioning what I want. 

Is there a slicker way to cancel/undo a dimension that is clicked on by mistake?