I've observed this problem using an old version of Tk (8.4.7). Maybe it's solved in newer versions, but I couldn't check. I happens in Linux, but not in Windows.
The problem happens when I try to type an accented character like á (this is á in HTML, in case that you cannot see correctly). To try this with an English keyboard, there should be an accent character if you press AltGr+#, for instance.
The problem is the following one. If I do:
> text .t
> pack .t
The accented characters work, and I can type á by pressing first the ´ character, releasing the key, and then typing the a.
But if I pack any other widget afterwards, for instance:
> frame .f
> pack .f
Then the accented characters stop working and I can only type a.
Finally, if I create another text widget:
> text .u
> pack .u
I can only type á in the second text, but the first one still doesn't work.
I've traced the binding for <Key> in the Text class. When I pack only the first text, .t, the binding executes only after I've hit the two keys:
tk::TextInsert .t á
And after I've packed the frame .f, it executes immediately after I hit each key:
tk::TextInsert .t {} <-- when I hit ´
tk::TextInsert .t a <-- when I hit a
Perhaps this is related to bug #1924761.