midend_process_key: allow Shift+Tab to pass through to the backend.

Previously, a button code of ('\t' | MOD_SHFT) from a frontend would have
the MOD_SHFT flag stripped by midend_process_key, resulting in a bare '\t'
passed to the backend. Now, this combination is allowed to pass through to
the backend. This will be used in the keyboard interface to Untangle, which
I'm about to add.

1 files changed, 3 insertions, 3 deletions

diff --git a/devel.but b/devel.but
index 4d205ac..577e74d 100644
--- a/devel.but
+++ b/devel.but
@@ -1145,9 +1145,9 @@ the \c{button} parameter:
 
 \dt \cw{MOD_CTRL}, \cw{MOD_SHFT}
 
-\dd These indicate that the Control or Shift key was pressed
-alongside the key. They only apply to the cursor keys, not to mouse
-buttons or anything else.
+\dd These indicate that the Control or Shift key was pressed alongside
+the key. They only apply to the cursor keys and the ASCII horizontal
+tab character \cw{\\t}, not to mouse buttons or anything else.
 
 \dt \cw{MOD_NUM_KEYPAD}