mvvm - WPF Combobox text binding issue on tab chage -

i working in wpf application follows mvvm.

i have used binding in combobox's text property , combo inside tab.

when ever switch tabs, combobox's text property cahnged getting fired , text set string.empty.

if don't want text ever empty, try:

view
<combobox text={binding comboxtext} ... />

edit comment:
<combobox text={binding comboxtext, targetnullvalue=somevalue} ... />

viewmodel

/*inotifypropertychanged property*/ private string comboxtext; public string comboxtext  {  { return comboxtext; }      set {        if (value != comboxtext)         {// value changed ->            if (!string.isnullorwhitespace(value))             {// value not null, empty, whitespace ->               comboxtext = value;          }            /*inpc code*/       }      } }