mvvm - WPF: Changing tabs makes Windowsformshost child disappear -

if can spare time, working on problem can't find solution on internet.

i need 2 tabs' richtextboxes bind same property. both richtextboxes hosted in wpf via windowsformshost. if alternate between tabs, 1 richttextbox dissapear (always first 1 visible). migrating app , far, forced use windowsforms richtextbox.

i hope managed convey problem - sorry, not native speaker.

thanks in advance

edit: asked provide clear example of problem. note. rewrote question. further, have uploaded micro app have isolated problem. click 2 tab buttons alternately , 1 richtextbox dissapear.

below, provide code if serves:

this mainwindow (xaml):

<stackpanel orientation="horizontal" height="35" margin="0,35,0,0" verticalalignment="top" >         <button x:name="tab1" command="{binding leftcommand}" content="left" minwidth="100" />         <button x:name="tab2" command="{binding rightcommand}" content="right" minwidth="100" />     </stackpanel>         <frame x:name="myframe"                 content="{binding path=currenttab, mode=twoway, updatesourcetrigger=propertychanged}"                 margin="5,70,0,0" navigationuivisibility="hidden"  />    

this viewmodel:

class mainwindowviewmodel : inotifypropertychanged {     public icommand leftcommand { get; }     public icommand rightcommand { get; }      private tabviewmodel mytabviewmodel { get; set; }     private pageleft mypageleft { get; set; }     private pageright mypageright { get; set; }      public mainwindowviewmodel()     {         this.leftcommand = new modelcommand(p => this.setselectedtab("left"));         this.rightcommand = new modelcommand(p => this.setselectedtab("right"));          this.mytabviewmodel = new tabviewmodel();          this.mypageleft = new pageleft() { datacontext = this.mytabviewmodel };         this.mypageright = new pageright() { datacontext = this.mytabviewmodel };          //initial view on         //this.setselectedtab("left");     }      private void setselectedtab(string param)     {         switch (param)         {             case "left":                 this.currenttab = this.mypageleft;                 break;             case "right":                 this.currenttab = this.mypageright;                 break;         }     }      private object _currenttab;     public object currenttab     {         { return _currenttab; }         set         {             if (value != _currenttab)             {                 _currenttab = value;                 notifypropertychanged_mainviewmodel();             }         }     }      public event propertychangedeventhandler propertychanged;      // method called set accessor of each property.       // callermembername attribute applied optional propertyname       // parameter causes property name of caller substituted argument.       private void notifypropertychanged_mainviewmodel([callermembername] string propertyname = "")     {         propertychanged?.invoke(this, new propertychangedeventargs(propertyname));     } } 

furthermore, have 2 pages (mypageleft, mypageright) use same viewmodel (tabviewmodel) , use same bit of xaml code:

<contentcontrol content="{binding path=mywindowsformshost, mode=twoway, updatesourcetrigger=propertychanged}" /> 

both pages use same tabviewmodel:

class tabviewmodel : inotifypropertychanged {     private windowsformshost _mywindowsformshost;      public windowsformshost mywindowsformshost     {         { return _mywindowsformshost; }         set         {             if (value != _mywindowsformshost)             {                 _mywindowsformshost = value;                 notifypropertychanged_tabviewmodel();             }         }     }      public tabviewmodel()     {         this.mywindowsformshost = new windowsformshost() { child = new richtextbox() { text = "test" } };     }      public event propertychangedeventhandler propertychanged;      // method called set accessor of each property.       // callermembername attribute applied optional propertyname       // parameter causes property name of caller substituted argument.       private void notifypropertychanged_tabviewmodel([callermembername] string propertyname = "")     {         propertychanged?.invoke(this, new propertychangedeventargs(propertyname));     } } 

the problem: if start app , click on 2 tab buttons alternatingly, 1 of framed richtextboxes dissapear.

if might need it, used dirty solution - although might not recommendable.

i extended event of switch tab buttons. takes rtf property of selected tab's richtextbox , infuses in other richtextbox. goes kinda this:

if (tab2 button clicked) this.myrtf = tab1.richtextbox.rtf; tab2.richttextbox.rtf = this.myrtf; 

note beginner's hack on overall questionable approach.

thanks read question!