I'm back !
I soldered directly a key into pins E0, E1 (instead of F0, F1, a mistake in my last post). Then edited the python file like this :
#rows=[F0, F1, F2, F3, F4, F5, F6, F7],
rows=[F0, F1, F2, F3, F4, F5, F6, E0],
#cols=[B7, D0, D1, D2, D3, D4, D5, D6, D7, C0, C1, C2, C3, C4, C5, C6, C7],
cols=[B7, D0, D1, D2, D3, D4, D5, D6, D7, C0, C1, C2, C3, C4, C5, C6, E1],
I substitued F7 for E0 and C7 for E1, so that my extra key "coordonate" is E0 - E1 in the keyboard matrix
Then changed the entry responsible for "F1" in the list keyboard_definition to map a "A" associated with my extra key:
...
#((4, 4), (1, 3), 'HID_KEYBOARD_SC_F1'),
((4, 4), (7, 16), 'HID_KEYBOARD_SC_A'),
...
Once opened in EasyAVR, strangely, the new key shows "O" (I changed the letter to 'HID_KEYBOARD_SC_Z', but it still display 'O' - edited that manually)
Builded then loaded the new firware.
The new key, connected directly to the controller, open the infamous Office windows, AquaKeyTest show the same ALT + Win + Shift + CTRL press simultaneously T_T
Either I've overlooked something obvious, or this is a broken chineese copy of a teensy2++
Got a pro-micro controller bought from a french retailler, i'll try the same thing with it, when I had found some motivation...