[lmi] Suspected wx-2.8.9 regression

[Greg Chicares]

To reproduce:

Start lmi
File | New | Illustration
Go to "Payments" tab
In "Dumpin" field, type a negative number like -1
Hit Tab

A messagebox appears:

Assertion '!unit_test_refocus_event_pending_' failed.
[file /lmi/src/lmi/mvc_controller.cpp, line 670]

To see the desired behavior: do the same thing, but hit
Enter instead of Tab: in that case,
  "-1 is too low: 0 is the lower limit."
appears in the static control at the bottom of the dialog.
That's the way it worked for Tab as well as Enter, with some
earlier version of wx-2.8.x (I can't easily say exactly which
wx version, but suspect it was approximately wx-2.8.3).