MS Office-like TaskPane Control

Imports System.IO

Public Class DocumentForm

    Private m_DocumentPath As String = ""
    Private m_CurrentStart As Integer = 0

    Public Property DocumentPath() As String
        Get
            Return m_DocumentPath
        End Get
        Set(ByVal value As String)
            m_DocumentPath = value

            If m_DocumentPath IsNot Nothing AndAlso File.Exists(m_DocumentPath) Then
                Try
                    rtbDocument.LoadFile(m_DocumentPath)
                Catch ex As Exception
                    rtbDocument.LoadFile(m_DocumentPath, RichTextBoxStreamType.PlainText)
                End Try

                Me.Text = Path.GetFileName(m_DocumentPath)
            Else
                MessageBox.Show("Cannot load document: " & Environment.NewLine & Environment.NewLine _
                                & m_DocumentPath, "Error Loading Document")
            End If
        End Set
    End Property

    Public Sub ClearSelection()
        rtbDocument.SelectedText = ""
    End Sub

    Public Sub FindText(ByVal argText As String)
        If argText.Length = 0 Then Return

        rtbDocument.Find(argText, m_CurrentStart, RichTextBoxFinds.None)
    End Sub

    Private Sub rtbDocument_SelectionChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles rtbDocument.SelectionChanged
        m_CurrentStart = rtbDocument.SelectionStart

        If rtbDocument.SelectionLength > 0 Then
            m_CurrentStart += 1 ' make sure it finds the NEXT match, not the current one
        End If
    End Sub
End Class