prevent JS crash when trying to decorate header cells, as those would produce from/to == null as .fromRow/.toRow would be < 0. Needs further work; hard to reproduce.
prevent JS crash when trying to decorate header cells, as those would produce from/to == null as .fromRow/.toRow would be < 0. Needs further work; hard to reproduce.

GerHobbelt/SlickGrid,GerHobbelt/SlickGrid,GerHobbelt/SlickGrid