c# - WPF Custom Control Design Error -

my application runs fine, error in visual studio driving me crazy. actual error is:

could not find part of path 'c:\program files (x86)\microsoft visual studio 12.0\common7\ide\emailtemplates'.

my program starts up, , populates combo box of .msg files in directory relative application. said, compiles , runs fine. have tried rebuilding, cleaning, etc. nothing works. cleaning seems fix it, until build again. going on??

main window:

<window x:class="abfsemailgenerator.mainwindow"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:custom ="clr-namespace:abfsemailgenerator"     title="mainwindow" height="700" width="600"> <grid>     <grid.rowdefinitions>         <rowdefinition height="auto"/>         <rowdefinition height="auto"/>         <rowdefinition height="auto"/>         <rowdefinition height="auto"/>     </grid.rowdefinitions>     <expander x:name="emailselectexpander" header="select email" horizontalalignment="right" width="592">         <custom:htmlviewer></custom:htmlviewer>     </expander>  </grid> </window> 

htmlviewer:

<usercontrol x:class="abfsemailgenerator.htmlviewer"          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"          xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"           mc:ignorable="d"           d:designheight="600" d:designwidth="600"> <grid>     <grid.rowdefinitions>         <rowdefinition height="auto"/>         <rowdefinition height="auto"/>         <rowdefinition height="*"/>         <rowdefinition height="auto"/>      </grid.rowdefinitions>     <grid.columndefinitions>         <columndefinition width="auto"/>         <columndefinition width="28*"/>         <columndefinition width="243*"/>     </grid.columndefinitions>      <label margin="3" grid.row="0">cc:</label>     <textbox x:name="cctext" margin="3" grid.column="1" grid.row="0" grid.columnspan="2" />     <label margin="3" grid.row="1">subject:</label>     <textbox x:name="subjecttext" margin="3" grid.column="1" grid.row="1" grid.columnspan="2"/>     <webbrowser margin="3,3,3,33"  x:name="bodybrowser" grid.row="2" grid.columnspan="3" verticalalignment="stretch" height="500" grid.rowspan="2"></webbrowser>     <combobox x:name="emailselector" grid.row="3" grid.column="0" margin="3" grid.columnspan="3" dropdownclosed="emailselector_dropdownclosed"/> </grid> 

htmlviewer code:

namespace abfsemailgenerator { /// <summary> /// interaction logic htmlviewer.xaml /// </summary> public partial class htmlviewer : usercontrol {     outlook.application oapp = new outlook.application();            private dictionary<string, dictionary<string, dynamic>> emaildict = new dictionary<string, dictionary<string, dynamic>>();      public htmlviewer()     {          initializecomponent();         populatecb();        }       private void populatecb()     {         string emailfolder = appdomain.currentdomain.basedirectory + "/emailtemplates";         emaildict.clear();         emailselector.itemssource = null;         foreach (var file in directory.enumeratefiles(emailfolder, "*.msg", searchoption.alldirectories))         {             ...         }     } } 

cannot create instance of 'htmlviewer'.

that suggests initialization may culprit.

in design mode don't want control trying work other setting basic , feel of control.

to keep operational activities minimum, may create null instance failures, best segregate code has high possibility of failure such:

 public htmlviewer()  {      initializecomponent();       if (!designerproperties.getisindesignmode(this)) // if not in design mode...do work.         populatecb();    } 

depending on how dependency properties setup, may not handling null , causing issues; if above code apply.