python - In TKinter, why does tkMessageBox bar me from modifying Entry objects? -

python - In TKinter, why does tkMessageBox bar me from modifying Entry objects? -

i'm using tkinter , have weird situation.

i've created little application has listbox, 2 buttons, , entry. 2 buttons add together , remove items listbox, respectively, , entry specifies name of item added. encapsulated in frame.

to right of frame near identical one, except listbox of frame contains items parented ones on left. basically, 'lists' or 'categories' created in first listbox, , items added lists in sec listbox.

tl;dr: here 3 screenshots of application in use, create things easier visualize.

in application, there can no 2 categories of same name. if there 2 categories of same name, tkmessagebox.showerror(...) called. works correctly , programme still functions correctly, except cannot highlight or modify either of entry fields anymore.

i @ first thought reason beingness set disabled or readonly, know cannot because buttons of programme still work, , when press 'add category', contents of entry field copied categories list , removed entry field. entry fields not modifiable, via code (.delete(...) , .insert(...) calls don't work) when set disabled or readonly, yet application able utilize these calls.

furthermore, when mouse on entry fields, cursor switches 'reading cursor' (like when mouse on text). when effort click, click , drag, or type, nil happens. it's if entry fields have permanently lost focus.

python listbox tkinter entry tkmessagebox