Hi Mark,
I guess the fundamental frustration is why LO interface operations are not identical to SU operations ?
why do we all have to do a mental mind flip to achieve the same results?
As to the particular topic - sorry I am not skilled at creating a descriptive gif animation
so let me try to describe in words
Scaled Drawing are great a great step forward and hope you push this further -
I want to throw AutoCad in the bin
Lets say I am designing a simple detail - say a retailing wall section in LO
A draw a rectangle to represent the strip footing , say 600mm x 300mm - its a first guess
Engineer comes back and says it needs to be 750mm x 350mm
IN SU this is simple, I just pick a line [edge] and move in the direction I want and type in 150 or 50
In LO I cannot do the same , I certainly don’t want to work out the % scale factor of the changes
Yes. I could use Dave’s workarounds… but why, why , why ??? isn’t it the same as SU?
While I have your attention 
Can I suggest the SU / LO team looks at maybe implementing this
Nudge command similar to used in CorelDraw

it allows the user to move the cursor within a command know distances on the x or y axis
- holding the shift key either multiplies or divides the increment size
Really handy when setting out dimensionally accurate work
Regards