#487 Various display bugs in beta

[Steve Keen]

Hi Russ, sorry for the vague ticket name, but a range of problems have turned up with this beta & I want to pass them on before a very busy day of talks in Colombia today.

Parameters seems to have been broken somehow--once created they can't be selected;an error message pops up instead.

The equations display tab no longer works--the program freezes and returns to the canvas.

[High Performance Coder]

Unable to reproduce either of those problems on either Linux or Windows 10, using the attached mky file.