When I write a disequation for an implicit plot, KmPlot freezes.
If I do the same with a cartesian plot, nothing happens and ">" is not red.
Equation editor has "≥" and "≤" symbols, so the user expects that disequations are supported.

Reproducible: Always

Steps to Reproduce:
1. Open KmPlot
2. Press "Create"
3. Press "Implicit Plot"
4. Write x+y>5
Actual Results:  
Freeze

Expected Results:  
Possible results:

1. Disequation drawn
Example: https://upload.wikimedia.org/wikipedia/commons/0/0c/Linear_Programming_Feasible_Region.svg

2. Operator ">" red colored (not supported)

3. Nothing happens, but no freeze occurs

Is it possible to insert "≥" using the equation editor and the software still freezes.
If disequations are not supported, this button should not be shown and ">"/"≥"/etc. should be red.