I figured it out
Linetype dialog to wnidow form;
Private Sub Button3_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
'Populates Combobox 2 with the current Drawing Linetypes
Dim db As Database = HostApplicationServices.WorkingDatabase
Dim t As Transaction = db.TransactionManager.StartTransaction()
Dim LD As New Autodesk.AutoCAD.Windows.LinetypeDialog
Dim dr As Windows.Forms.DialogResult = LD.ShowDialog 'Show the Dialog
If dr = Windows.Forms.DialogResult.OK Then 'If user clicked OK then
Dim str As String = ""
Dim ltyp As ObjectId
ltyp = LD.Linetype
Dim sld As LinetypeTableRecord = CType(t.GetObject(ltyp, OpenMode.ForRead), LinetypeTableRecord)
str = sld.Name
TextBox4.Text = str
End If
t.Dispose()
db.Dispose()
End Sub