The idea behind this wish is to be able to select all the dimensions whose numerical value have been manually modified to a custom value.
I often modify certain dimensions to make their displayed numerical value more appropriate if the latter does not correspond to the settings of my custom Annotation styles. For example if the latter is set to show numbers with a precision up to 0,1 mm, a distance such like 6,795 mm will be displayed as 6,8 mm instead. I know that I could modify the entire Annotation style to a precision of 0,001 mm or anything else, but that’s not the case. Sometimes, I also need to adjust some dimensions of the part just by a small amount, but instead of spending lots of time to make an entirely new 3d geometry and extract data from it to make a new drawing, I simply modify a certain dimension from the existing drawing, because it’s a quicker way to do the necessary changes.
And this is where the things could get totally wrong, because once the value of a basic dimension is being modified, it will stay the same (as it should) even if I move its control points to another distance. This is fine, unless I forget which dimension was original and which was modified additionally. So, I’m forced to manually check every dimension with the ! _Distance command, which takes lots of time and mouse clicks on more complex drawings. This is where a single-click command such as “Select modified dimensions” would let me see immediately which dimension is modified.
Hi Pascal, it’s funny that I have never seen this command before, even though I use Rhino for many years. 
Is this a newly added command? For some reason it’s not included in the Dimensions toolset, as you can see in my screenshot below. I will copy it there immediately, because it’s very usable for me. Thanks for the tip!
Yes, it is. Nobody remembers all Rhino commands. All top level experts and instructors who post in this forum made similar mistakes.
I’m glad that this particular command already exists and I don’t have to wait for it to be implemented in the future.