adds some utility methods,
-for enable and disable checkboxes
-for making patterns from different filters
modifies history if save option is enabled in preferences
alters doctsrings
checkbox filtering integrated with filter method and EVT_CHECKBOX only looks at checking and unchecking event and related stuff
sets window ison
shows history list when history tool selected
some modifications in populate method
updates comments
updates comments
updated
contains utility functions used by other scripts, join_path opj moved into it