SSMS 2017: Open SQL Files in existing SSMS app with raised admin permissions? I realise this is an old chestnut, but does anyone have a definitive solution?

When SSMS (2017) is 'run as administrator', double clicking a SQL file in explorer will open another new instance of SSMS (and not open the file). This is not good. Double clicking a SQL file should open it in the existing open SSMS app.

Is there a solution to this? 

What reasons are there to 'run as admin' by default or can this be turned off without impacting functionality?

Many thanks,

James
In SSMS use Ctrl+O to open the file instead of double-clicking in explorer.