When the user hovered over a number input field, pressed Enter and then
typed in '0', confirming the input would always cancel the action. This
is because in this particular case `ui_textedit_begin` is called
instead of `ui_numedit_begin`. This function will not set
`data->startvalue` (leaving it at `0`) which will then trigger the
cancel in `ui_apply_but_NUM` which checks if the input changed (by
comparing the entered value with `data->startvalue`).
The fix makes sure that when `ui_textedit_begin` is called on a number
button, the `data->startvalue` is set correctly like in
`ui_numedit_begin`.
Breaking commit: rBSeb06ccc32462beaacbb114d6d0e450b6fc911047
Note: This also affects pressing tab to move to a new number field and
entering '0'. The fix will also cover this case.
Reviewed By: Severin, #user_interface
Maniphest Tasks: T88058
Differential Revision: https://developer.blender.org/D11168
ec30cf0b74