wpf - Expose ToolTip DependencyProperty on custom DataGridTextColumn -

i know can style column , set tooltip way, want have real tooltip property on grid column. having trouble exposing tooltip property textblock before created. custom column.

public class datagridtextcolumn : system.windows.controls.datagridtextcolumn {     public static readonly dependencyproperty texttrimmingproperty = dependencyproperty.register(         "texttrimming", typeof (texttrimming), typeof (datagridtextcolumn),         new propertymetadata(default(texttrimming)));      /// <summary>     ///     horizontalalignment dependency property.     /// </summary>     public static readonly dependencyproperty horizontalalignmentproperty =         dependencyproperty.register(             "horizontalalignment",             typeof (horizontalalignment),             typeof (datagridtextcolumn),             new frameworkpropertymetadata(horizontalalignment.left, frameworkpropertymetadataoptions.affectsarrange), validatehorizontalalignmentvalue);      public datagridtextcolumn()     {         elementstyle = application.current.resources["datagridtextstyle"] style;         editingelementstyle = application.current.resources["datagrideditingtextstyle"] style;     }      /// <summary>     ///     texttrimming, works in read-only mode     /// </summary>     public texttrimming texttrimming     {         { return (texttrimming) getvalue(texttrimmingproperty); }         set { setvalue(texttrimmingproperty, value); }     }      /// <summary>     ///     horizontalalignment property.     /// </summary>     public horizontalalignment horizontalalignment     {         { return (horizontalalignment) getvalue(horizontalalignmentproperty); }         set { setvalue(horizontalalignmentproperty, value); }     }      internal static bool validatehorizontalalignmentvalue(object value)     {         var ha = (horizontalalignment) value;         return (ha == horizontalalignment.left                 || ha == horizontalalignment.center                 || ha == horizontalalignment.right                 || ha == horizontalalignment.stretch);     }      protected override frameworkelement generateelement(datagridcell cell, object dataitem)     {         var element = (textblock) base.generateelement(cell, dataitem);         element.texttrimming = texttrimming;         element.horizontalalignment = horizontalalignment;         return element;     } 

the tooltip has attached textblock.

is want:

element.tooltip = new tooltip { content = new textblock { text = "da tooltip!" } }; 

?...