Also, when a filter PID is selected in the drop down list box (but not yet applied), you can search backwards and forwards through the un-filtered log file for changes in the filter PID's true/false status. Use the two arrow buttons next to the filter/funnel button.

Ctrl+PgUp and Ctrl_PgDown are the equivalent hot keys for searching.
Ctrl+F is the hotkey for the filter/funnel button.

Regards
Paul