Custom textbox that can only enter numbers in WPF

Keydown event: optimize tab and rightctrl

   Private     Void  Tbcount_keydown (  Object  Sender, keyeventargs E)
{
Textbox txt  =  Sender  As  Textbox;

  //  Shield illegal buttons 
    If  (E. Key  > =  Key. numpad0  &&  E. Key  <=  Key. numpad9)  |  E. Key  =  Key. Decimal  |  E. Key. tostring ()  =    "  Tab  "  )
{
  If  (Txt. Text. Contains (  "  .  "  )  &&  E. Key  =  Key. decimal)
{
E. Handled  =    True  ;
  Return  ;
}
E. Handled  =     False  ;
}
  Else     If  (E. Key  > =  Key. D0  && E. Key  <=  Key. D9)  |  E. Key  =  Key. oemperiod)  &&  E. keyboarddevice. Modifiers  ! =  Modifierkeys. Shift)
{
  If  (Txt. Text. Contains (  "  .  " )  &&  E. Key  =  Key. oemperiod)
{
E. Handled  =     True  ;
  Return  ;
}
E. Handled  =     False  ;
}
 Else  
{
E. Handled  =     True  ;
  If  (E. Key. tostring ()  ! =     "  Rightctrl  "  )
{
MessageBox. Show (  This  . Resources [ "  Txt_innerpage_connpointmanage_tabmyconnpoint_addmycloudseenum_prompt  "  ]. Tostring (),  This  . Resources [  "  Txt_innerpage_connpointmanage_tabmyconnpoint_addmycloudseenum_prompttitle  "  ]. Tostring (), messageboxbutton. OK, messageboximage. Warning );
}
}
} 

Textchanged event:

 

 Private    Void  Textbox_textchanged (  Object  Sender, textchangedeventargs E)
{
  //  Block Chinese Input and illegal character paste Input  
  Textbox  =  Sender  As  Textbox;
Textchange [] Change  =    New  Textchange [E. Changes. Count];
E. Changes. copyto (change,  0  );

  Int  Offset  =  Change [  0  ]. Offset;
  If  (Change [  0  ]. Addedlength  >    0  )
{
  Double  Num  =     0  ;
  If  (  !  Double. tryparse (textbox. Text,  Out  Num ))
{
Textbox. Text  =  Textbox. Text. Remove (offset, change [ 0  ]. Addedlength );
Textbox. Select (offset,  0  );
}
}
}