[RESOLVED] What is the best way to close all open child forms

[kevintaw]

Hello, I need some help.

How (what is the best way) to close all open child forms in VB.NET?

Here is my code and screenshot of the program.

Public Sub ShowForm(ByVal Frm As Form)
        For Each frmClose As Form In MainForm.MdiChildren
            frmClose.Close()
            frmClose.Dispose()
        Next
        With Frm
            .MdiParent = MainForm
            .Show()
            .WindowState = FormWindowState.Maximized
        End With
    End Sub

Private Sub TsbTPR_Click(sender As Object, e As EventArgs) Handles TsbTPR.Click
        ShowForm(FrmPermintaan)
    End Sub

When I click another form, it seems like the "form closing" process is not really neat and see some blink.

Video: https://www.screencast.com/t/M8NYwOVDH

Also, when I use the above code and I click the same form, it gives this error:
Cannot access a disposed object.


Please help