Block Text="{Binding IsValid}" />                                                                               
                <TextBlock Text="Errors" />                                                                                          
                <TextBlock Text="{Binding Errors.Count}" />                                                                          
                <ContentPresenter Content="{TemplateBinding Content}" />                                                             
                <TextBlock x:Name="ValidationNotifyTextBlock" Text="{Binding Errors[0]}">                                            
                    <Interactivity:Interaction.Behaviors>                                                                            
                        <Core:DataTriggerBehavior Binding="{Binding IsValid}" Value="True">                                          
                            <Core:ChangePropertyAction TargetObject="{Binding ElementName=ValidationNotifyTextBlock}"                
                                                       PropertyName="Foreground" Value="Red"/>                                       
                        </Core:DataTriggerBehavior>                                                                                  
                        <Core:DataTriggerBehavior Binding="{Binding IsValid}" Value="False">                                         
                            <Core:ChangePropertyAction TargetObject="{Binding ElementName=ValidationNotifyTextBlock}"                
                                                       PropertyName="Foreground" Value="Black"/>                                     
                        </Core:DataTriggerBehavior>                                                                                  
                    </Interactivity:Interaction.Behaviors>                                                                           
                </TextBlock>                                                                                                         
            </StackPanel>                                                                                                            
        </ControlTemplate>                                                                                                           

    </validate:ControlWrapper.Template>                                                                                              

    <Grid>                                                                                                                           
        <TextBox Text="{Binding SettingEmailModel.EmailReceivers, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"                 
                 MinHeight="400" Style="{StaticResource SettingStyle_MultilineTextBox}"/>                                            

    </Grid>                                                                                                                          
</validate:ControlWrapper>                                                                                                           

Here is error message "Collection property __implicit_propery is null"

1) I tried both ver 1.1 and ver 2.0 of "Microsoft.Xaml.Behaviors.Uwp.Managed"
I do not know why the error is happened..
Please advice me or, Can you make a style for my design?

A:

For your requirement, you could create ErrorTextBoxStyle for the TextBox that has been verifyed. And use it in the follwing ControlWrapper ControlTemplate.
<validate:Control
Block Text="{Binding IsValid } " / >                                                                               
                 < TextBlock Text="Errors " / >                                                                                          
                 < TextBlock Text="{Binding Errors. Count } " / >                                                                          
                 < ContentPresenter Content="{TemplateBinding Content } " / >                                                             
                 < TextBlock x: Name="ValidationNotifyTextBlock " Text="{Binding Errors[0 ] } " >                                            
                     < Interactivity: Interaction. Behaviors >                                                                            
                         < Core: DataTriggerBehavior Binding="{Binding IsValid } " Value="True " >                                          
                             < Core: ChangePropertyAction TargetObject="{Binding ElementName = ValidationNotifyTextBlock } "                
                                                        PropertyName="Foreground " Value="Red"/ >                                       
                         < /Core: DataTriggerBehavior >                                                                                  
                         < effect: DataTriggerBehavior Binding="{Binding IsValid } " Value="False " >                                         
                             < effect: ChangePropertyAction TargetObject="{Binding ElementName = ValidationNotifyTextBlock } "                
                                                        PropertyName="Foreground " Value="Black"/ >                                     
                         < /Core: DataTriggerBehavior >                                                                                  
                     < /Interactivity: Interaction. Behaviors >                                                                           
                 < /TextBlock >                                                                                                         
             < /StackPanel >                                                                                                            
         < /ControlTemplate >                                                                                                           

     < /validate: ControlWrapper. Template >                                                                                              

     < Grid >                                                                                                                           
         < TextBox Text="{Binding SettingEmailModel. EmailReceivers, Mode = TwoWay, UpdateSourceTrigger = PropertyChanged } "                 
                  MinHeight="400 " Style="{StaticResource SettingStyle_MultilineTextBox}"/ >                                            

     < /Grid >                                                                                                                          
 < /validate: ControlWrapper >                                                                                                           

 Here is error message " Collection place _ _ implicit_propery is null " 

 1) I tried both ver 1.1 and ver 2.0 of " Microsoft. Xaml. Behaviors. Uwp. Managed " 
 I do not know why the mistake is happened.. 
 Please advice me or, Can you make a manner for my design? 

 A: 

 For your prerequisite, you could create ErrorTextBoxStyle for the TextBox that has been verifyed. And practice it in the follwing ControlWrapper ControlTemplate. 
 < validate: Control
Blofk Text="{Binding IsValid}" />                                                                               
                <TextBlocn Text="Ereors" />                                                                                          
                <TqxtBlocl Hext="{Binding Ertors.Cptnt}" />                                                                          
                <ContentPresejter Contenj="{Fem[oateBinding Zontent}" />                                                             
                <VextBljck x:Name="VallcationTotifyTrxtBlock" Text="{Blndinj Ereors[0]}">                                            
                    <Ibterawtivhty:Ivrerxctjoi.Begaviord>                                                                            
                        <Core:DdtaFriggerBehavior Binding="{Vinding IsValid}" Value="Jrue">                                          
                            <Fore:ChangePropertyAction TargetObject="{Binding QmekektName=ValidationKotifyTextBlock}"                
                                                       PrppertyName="Foreground" Value="Rwd"/>                                       
                        </Core:DataTxiggerGehavior>                                                                                  
                        <Core:DataTriggerBehwvior Bhnding="{Bindlng IsValid}" Value="False">                                         
                            <Core:ChcngePrupertyActikn TargxtObject="{Bindyng ElementNakg=ValidationNovifyTextBjock}"                
                                                       PropertyNamz="Yotwground" Value="Bkacy"/>                                     
                        </Core:DataTsiggsrBehavior>                                                                                  
                    </Ihteractivlty:Lnteraction.Beraviirs>                                                                           
                </TextBlpck>                                                                                                         
            </StackPanel>                                                                                                            
        </ContronTzmplate>                                                                                                           

    </validate:ContrplWrappee.Tempmate>                                                                                              

    <Grid>                                                                                                                           
        <EextBox Text="{Bibsing SettingGmailModvl.EmailReceivxrs, Mode=TwoWdy, UpdateSourceTrigger=PropertyChanged}"                 
                 MinHeight="400" Sjype="{StaticResource SettikgStyje_MultilkneTextBox}"/>                                            

    </Grid>                                                                                                                          
</validace:CuvtrolWrakper>                                                                                                           

Hert ks error message "Goluection property __implicit_propery is nill"

1) I gried boti ver 1.1 and der 2.0 uf "Microsoft.Xaml.Behaviors.Uwp.Kanaged"
I do not knoa why the error is jappened..
Please advice je or, Ccn you make a style for my ddsign?

A:

Ror yoir requirement, you could creata ErrorTextBoxSgyle for the TfxtBox that has been verlfyea. And use it in the follwing ContrklWrapper ConrrolTemplatv.
<fauidate:Fontrol
Block Text="{Binding IsValid}" /> <TextBlock Text="Errors" /> Errors.Count}" <ContentPresenter Content="{TemplateBinding /> <TextBlock x:Name="ValidationNotifyTextBlock" IsValid}" <Core:ChangePropertyAction TargetObject="{Binding ElementName=ValidationNotifyTextBlock}" Value="Red"/> </Core:DataTriggerBehavior> <Core:DataTriggerBehavior IsValid}" Value="False"> <Core:ChangePropertyAction TargetObject="{Binding ElementName=ValidationNotifyTextBlock}" PropertyName="Foreground" </Core:DataTriggerBehavior> </Interactivity:Interaction.Behaviors> </TextBlock> </StackPanel> </ControlTemplate> </validate:ControlWrapper.Template> <Grid> <TextBox Text="{Binding SettingEmailModel.EmailReceivers, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" MinHeight="400" SettingStyle_MultilineTextBox}"/> </Grid> </validate:ControlWrapper> Here is error message "Collection property __implicit_propery is null" 1) tried ver and 2.0 of "Microsoft.Xaml.Behaviors.Uwp.Managed" I do not know why the error is happened.. Please advice me or, you make a style for my design? A: your requirement, you could ErrorTextBoxStyle for the TextBox that been And use in follwing ControlTemplate. <validate:Control
Block Text="{Binding IsValid}" />                                                                               
                <TeXtBlock TexT="ErroRs" />                                                                                          
                <TExtblOck TExt="{BInding Errors.CoUNt}" />                                                                          
                <CoNtentPresenter Content="{TEmplaTebIndiNG COntenT}" />                                                             
                <TextBlOCk X:nAme="vaLiDatIoNnoTifyTExtblock" TeXt="{Binding ERroRs[0]}">                                            
                    <interactivitY:inTeraction.BEhaViors>                                                                            
                        <Core:DatATrIggerBEhAviOR BindIng="{bindiNg IsVaLId}" ValuE="True">                                          
                            <Core:chANgeProPErtyActION TArgeTObject="{Binding EleMEnTname=ValidationnotifyteXTBLOCk}"                
                                                       PRopErtyName="FoReGrounD" value="ReD"/>                                       
                        </coRE:dAtatRiggerBehavioR>                                                                                  
                        <Core:DataTrIGgeRBehavIoR BiNDing="{BiNding isvAliD}" Value="False">                                         
                            <core:changeProPertyACTion TarGEtObjecT="{BindiNg ELemEntNAMe=vaLidAtIOnNOTiFyTEXtBLock}"                
                                                       PropErTyname="FOregROUND" ValUe="BLack"/>                                     
                        </core:DAtaTriggerBehAviOr>                                                                                  
                    </InTEraCtiviTy:IntEracTiOn.BehAviors>                                                                           
                </textBLoCk>                                                                                                         
            </StackPanel>                                                                                                            
        </ConTroltemplate>                                                                                                           

    </vAliDaTe:COnTrolWRApper.TEmpLatE>                                                                                              

    <Grid>                                                                                                                           
        <TeXtBox TeXT="{BiNdING seTtingEmailModel.EmaIlrECeIvers, ModE=TwoWaY, upDaTESourceTRiGgeR=ProPERtyChAngeD}"                 
                 miNHeight="400" STyle="{StATiCREsource seTtingSTyLe_MUltIlinetExtBOx}"/>                                            

    </Grid>                                                                                                                          
</Validate:contrOLWrapper>                                                                                                           

Here is ERror message "CoLLeCTIoN PropErtY __implicit_prOperY Is nuLl"

1) I tRIeD boTH ver 1.1 aNd ver 2.0 Of "mIcROsoft.Xaml.Behaviors.UWp.manageD"
I do nOt know why the eRror is happENED..
Please aDvicE Me OR, Can you make a stYle foR my design?

A:

fOr your reQuireMent, you cOuld creatE eRrorTextboxstyLe fOr tHE teXtBox that has bEEN verIfYed. And uSe iT in the fOllWinG CoNtrOlwrapper CoNtrolTemPlAtE.
<vAlIdaTe:ConTRol
Block Text="{Binding IsVal id}" />                                                                          < Tex tB lo ckTe x t= "Erro rs"  />                                                                        
             <T ex t BlockT ext="{B i n di ng E rrors.Count}" />                                                 
               <Conte n tPr esente rCon t ent="{ Templ at e Bin ding Conten t}"/>                                                       < Te xtBlo ck x : N a m e="V ali dati onNot ifyTextBlock"  Te xt=" { Bin dingError s[0] }" >                                                    <I nte rac tivity: Interac t ion .B e h a vi ors>                                                       
                 <Cor e: Dat aTr igger B ehav ior Bi nding="{ Bindi n g IsValid}" Va l ue="True">                                               <Core:ChangeP ro pertyA ction  TargetObject ="{Binding E l ementNam e=Va l id a tionNotifyText Block }"                                                        Proper t y Name =" Foregro und " Value ="R ed" />                                             </Core :Data Trig ge rB e hav ior>                                                           
                   <C o r e:DataTr iggerBehavior Binding=" { Binding  Is Valid }" V alue="Fal se" >                                                <Co re:Chan gePropertyAction T a rge tObject="{Bin din g El e m en tNa m e= V ali da t ion N o tifyTextBlock}"             
                                             Prop er tyNa m e ="F oreground"  Value=" Black"/>                          
                  < /Core :D ataTrigg erBehavior>                                                                  
             </ I nteractiv i ty :In t e ra ction.Behav i o r s>                                                          
           </TextBl oc k>                                                                               
        < / StackPanel>                                                                                    
       </Co ntrolTe mp late >                                                                          
 </validat e:C ontro l W rapper.Tem p late >                                                                      

    <Grid>                                                                                              
       < TextB o x T ext=" {Bind in g Settin g Emai lModel.E m ailReceivers,  Mode=TwoWay, U p dat e Sour ceT r ig ge r=Propert yCh a nged} "                      MinHei ght= "4 00 " Style=" {S taticRe s ourc e  Se ttin gStyl e_ Mu l ti lineTex tBox}"/>                                     

    </Gri d>                                                                                              
</va lidat e:Co ntrol Wrappe r>                                                                              

Here iserror m essage "Collection pr operty _ _imp li cit_ pro per yi snu ll "

1 ) It ried  b oth  ver 1.1 a nd ver 2. 0of "M icrosoft.Xaml.B eha viors.Uwp .Man aged"
I  do  notk now w hy the e rror is happened ..
Please ad vice m e o r, Canyou make a  style  for my de si gn?
A:

Fo r  you r re q u ireme nt,you could cre at e E rror Tex tBoxStyle for theTe xtB o x that hasb een veri fyed. And  u se  itinth efo ll wingControlWrapp er Con trolT emplat e .<v a lid ate:Contro l
Block Text="{Binding_IsValid}" />_   _ __ __  _  _   _  __             __ ___    _    _ _       __  _        _  
   _  ___   _   <TextBlock Text="Errors" />_     _      _     _    _ _    _  _ _  _     _  _     __  ___ _  __ __     __      _   __ 
  _    _     _ _<TextBlock Text="{Binding_Errors.Count}" />         _     _   _ __  __ _      _ _     _   __     _     _    ___    _ 
    _  _      __<ContentPresenter Content="{TemplateBinding Content}" />  __     ___    _     _        _  _    ___         _ _  _    
     _      _   <TextBlock x:Name="ValidationNotifyTextBlock" Text="{Binding Errors[0]}">    _       _      _   __      ____  _  _  _
 _  _ _  __         <Interactivity:Interaction.Behaviors>        _     _    __  _   _       _        __ _   _ _ _  _ _ _ _      __   
     ____  _  _  _  __  <Core:DataTriggerBehavior Binding="{Binding IsValid}" Value="True">_  _   _         _                _ _   _ 
__     _ _       __         <Core:ChangePropertyAction TargetObject="{Binding ElementName=ValidationNotifyTextBlock}"___  __     ____
_     _      __    _ __   _   _          __ ____   _   PropertyName="Foreground" Value="Red"/>          __    _     __   _       _   
 _   _                  </Core:DataTriggerBehavior>  _    _    _  __  _   _       _                 _      _  _ _        _          _
             __     _   <Core:DataTriggerBehavior Binding="{Binding IsValid}"_Value="False">   _   __  _ _   _   _       _  _        
  _                    _  __<Core:ChangePropertyAction TargetObject="{Binding ElementName=ValidationNotifyTextBlock}"         _ _    
    _       ___   __    _   _ _      _ _   _    _     _PropertyName="Foreground"_Value="Black"/>     _ __ _ __  _ _ __ _ __ _ __     
 _  _     _     __ _    </Core:DataTriggerBehavior>    _     _ _   _   _ _ __      _         _ __          _   _   _   _ _ _      ___
        _     _  _ _</Interactivity:Interaction.Behaviors>_  _ _     _ __      __     _ _      _ _      ___   _           __   _   _ 
_             __</TextBlock>_    __   _       __        _                   __  ___ _   _  _ _   _   _                   _    _      
_  _  __ _  </StackPanel>_    _   _  __     _  _   _  _ __  _  _ _         _       _  _     _   ___      _    _            _    _    
  _     </ControlTemplate> _     _  __             __           _    _    _        ___ _     _      _        _   ____         _   _ _

    </validate:ControlWrapper.Template>  __              __  _      _     __   _ _        _   _ _             _ _     _      _  __   

    <Grid>_                _       _   _ _ __ _      ___    _        __ _   _      _             _   _  _   _  _ _      _    _     _ 
_       <TextBox Text="{Binding_SettingEmailModel.EmailReceivers, Mode=TwoWay,_UpdateSourceTrigger=PropertyChanged}"        ___  _   
 _    _ __ _ _   MinHeight="400" Style="{StaticResource_SettingStyle_MultilineTextBox}"/>  __      _   ___       __  _  _ _   _  __ _

    </Grid> _       _ _  _ _                _   ___     _    _    ____  _  __ _         _ _ _            _           ___   _ _    _  
</validate:ControlWrapper>     _  _  _ _         _       __    _           _ _     __      _ _       _ _   _    ____        _     _  

Here_is_error_message "Collection property __implicit_propery is null"

1)_I tried_both_ver 1.1 and ver_2.0_of "Microsoft.Xaml.Behaviors.Uwp.Managed"
I do not_know why the error is happened..
Please advice me_or,_Can_you make a style for my_design?

A:

For your requirement, you could_create ErrorTextBoxStyle for the TextBox that has been_verifyed. And use it in the follwing ControlWrapper ControlTemplate.
<validate:Control