Filtering of next action list for multiple contexts or projects

Currently when filtering the next action list it is only possible to select one context or project.

The filtering of next actions would be far more useful if it could include multiple contexts or projects. For example when I am at work I would like to see tasks under multiple contexts like “Office” and “Phone” as I can do either in that situation.

It would also be useful to be able to select both a Project, Label or Context. Choosing two or more of these would narrow down the next actions much more precisely.

Perhaps the filtering could be done by check box rather than drop down list.