It seems that you can use keyboard equivalents when in the THINK Find dialog. The following list was posted by Symantec (not sure if these are in the manual, but CMD-S and CMD-H work in both Versions 5,6 and 7.) We had noticed on our own that these two work:
Command-S Select all source files (multi-file-find search gets turned on)
Command-H Select all header files (multi-file-find search gets turned on)
Symantec Tech Support posted the following to the Internet:
"The new find dialog supports command key equivalents for all items in the [find] dialog: