Looks to me like Keybinder is getting confused by the new HEAD configuration vs users previous CB configuration.
At startup, Keybinder merges its view of the menu structure with the users previous <personality>.Keybinder20.conf, and rewrites it.
Disabling/Re-enabling keybinder makes it do a clean rebuild of both it's view of the current menu structure and the users previous settings.
I suspect that keybinder is mistakenly using the global keybinding id of a previous CB version instead of the current HEAD setting during the merge of old to new bindings. Global key bindings are a bitch to handle. They have no label. If an old (or non-existent) id is assigned to the global, it'll be connected to a galaxy far far away.
I'll take a look at it. It'll take some time.
Debugging Keybinder is always a time sink.
Reference: main.cpp line 761
m_pAccelEntries[6].Set(wxACCEL_SHIFT, WXK_TAB, idShiftTab);
@Miguel Gimenez
Are you saying that you are experiencing that Ctrl-Tab is doing the function of Shift-Tab ?