Anybody on Windows need to triple-click to add a library emitter or scene to the stage? This seems to be an issue on some systems, and I may have found a workaround.
In the Windows Control Panel - Mouse Properties, set the double-click speed slider to the slowest setting.
Does that fix the issue for you in PI?
Yep that helps, i had it set mid range, but i have folders set to single click so never really need double click, it has been doing my head in but never really looked into sorting it out 
Right click the Start button bottom left of the desktop - Settings - Devices - Mouse - Additional mouse options (in blue on the right)
Or click the Start button, Settings above the Power button - Devices - Mouse - Additional mouse options (in blue on the right)
Or right click the Start button - Search - type in ‘Control Panel’
Thank You Alan and GID - – that problem had been vexing me for some time and it was annoying and had no idea that was what the problem was…great job! Roman.
ya, i have to do multiple clicks as well, Thanks @Alan_Lorence
@Gid.Joiner Thanks for the tip
why is there no drag & drop in PI and only 2xclick?
There’s also single-click in stage to add the selected emitter – there’s a preference to turn that on/off.
Drag & drop has been on the list for a while, but bigger features keep taking priority. We’ll eventually get it in there I hope.