If you've chosen `Basic Bindings' on the jstools Global Preferences panel, you can use the following keyboard commands to edit text (in large text windows, and also in oneline text fields, except as noted):
Delete - delete the character before the insertion point
Control-h - delete the character before the insertion point
Backspace - delete the character before the insertion point
Left and right arrows - move one character left or right
Up and down arrows - move one line up or down (1)
Home key - move to the beginning of the line
End key - move to the end of the line
Page Up key - scroll back one screenful (1)
Page Down key - scroll forward one screenful (1)
Control-v - insert the X Windows selection (highlighted text) at the insert point
Control-slash - select the entire contents
Control-backslash - clear the selection
(1) Only available in multiline text windows, for obvious reasons