Grid header's combofilter with 'multiselection' doesn't work.

I want to use grid header’s combofilter with ‘multiselection’ option in dhtmlxSuite v.6.5.1 Professional.
It works in recent suite version but not in old version.
Is there a way to implement this feature or get fixed version?

Here’s code snippet:

Combo multiselection functionality was added in the v7.2 update:

Please, try to update your dhx.Suite package.