Cannot set focus to textbox - vb.net

Question

I am using VB and trying to select a portion of the text in a textbox of a separate form. However, I can't seem to find a good way to access the textbox from the other form, although the textbox is public (I am new to VB).
Currently, I'm trying to do this by calling a function located in the form (the form with the textbox), and then focusing on the textbox and selecting/highlighting the text. But it still doesn't work:
Public Sub GetFindLoc(ByVal lngStart As Long, ByVal intLen As Integer)
frmFind.Hide()
MessageBox.Show(ActiveForm.Name)
MessageBox.Show(txtNotes.CanFocus())
txtNotes.Focus()
txtNotes.Select(lngStart, intLen)
frmFind.Show()
End Sub
With this, I first hide the original form, and then try to select the text, and bring back the form. It shows that the active form is the one which I'm trying to select the text on, but it returns false on CanFocus().
Any help would be appreciated, thank you!

Answer 1

Hmm. This was more fiddly than I thought. You need to pass a reference to the other form:
Main form:
Public Class frmNotes
'This is the main form
'This form has a textbox named txtNotes and a button called btnShowFind
'txtNotes has .MultiLine=True
Private mfrmFind As frmFind
Private Sub btnShowFind_Click(sender As Object, e As EventArgs) Handles btnShowFind.Click
If mfrmFind Is Nothing OrElse mfrmFind.IsDisposed Then
mfrmFind = New frmFind(Me)
mfrmFind.Show()
Else
mfrmFind.BringToFront()
End If
End Sub
End Class
Finder form:
Public Class frmFind
'This form has a textbox called txtFind and a button called btnFind
Private mfrmParent As frmNotes
Sub New(parent As frmNotes)
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
mfrmParent = parent
End Sub
Private Sub btnFind_Click(sender As Object, e As EventArgs) Handles btnFind.Click
If txtFind.Text = "" Then
MsgBox("Please enter text to find", MsgBoxStyle.Exclamation)
Exit Sub
End If
Dim intSearchBegin As Integer = mfrmParent.txtNotes.SelectionStart + 1
Dim intStart As Integer = mfrmParent.txtNotes.Text.IndexOf(txtFind.Text, intSearchBegin)
If intStart > -1 Then
mfrmParent.txtNotes.Select(intStart, txtFind.Text.Length)
mfrmParent.txtNotes.Focus()
mfrmParent.BringToFront()
Else
mfrmParent.txtNotes.Select(0, 0)
MsgBox("No more matches")
End If
End Sub
End Class

Answer 2

Public Class frmFind
Private Sub btnFind_Click(sender As Object, e As EventArgs) Handles btnFind.Click
Dim search As String = TextBox1.Text.Trim
Dim pos As Integer = frmNotes.txtNotes.Text.IndexOf(search)
If pos > 0 Then
frmNotes.txtNotes.Focus()
frmNotes.txtNotes.Select(pos, search.Length)
End If
End Sub
End Class
This is just a "find" form with 1 textbox and 1 button which will highlight the first occurrence of the string in TextBox1 that it finds in txtNotes on the other form. If you want it to find whitespace as well, then remove the Trim function. You can add code to find other occurrences or go forward/backward.