VB.NET - TabControl中的表格在關閉後未打開它

Question

我從打開窗體的地方獲取ToolStripMenu。表格在TabControl中打開，放置在Split Container的一個面板中。我也在Split容器中放置了一個按鈕，它關閉了任何選定的TabPages（其中表單打開）。問題是，當我在新的TabPage中打開窗體並通過此按鈕關閉它時，窗體不再打開。爲什麼？ ....這裏是我的代碼：

Private Sub SearchItemsAPOToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles SearchItemsToolStripMenuItem.Click 

     'Define new page in Tab control and form to open in It 
     Dim PageNew As New TabPage() 
     Dim FrmItem As New Search_Items 

     'Define where and how form should open 
     FrmItem.TopLevel = False 
     FrmItem.Dock = DockStyle.Fill 
     FrmItem.FormBorderStyle = FormBorderStyle.None 

     'If form allready opened in TabPage, only send focus to It 
     If Application.OpenForms().OfType(Of Search_Items).Any Then 

      For Each page As TabPage In TabControl1.TabPages 

       If page.Text = "Search Items" Then 

        TabControl1.SelectedTab = page 

       End If 

      Next page 

      'If form not allready opened, we open It in Tab control and send focus on that TabPage 
     Else 

      PageNew.Controls.Add(FrmItem) 
      PageNew.Text = "Search Items" 
      TabControl1.Visible = True 
      TabControl1.TabPages.Add(PageNew) 
      FrmItem.Show() 
      BtnTab.Visible = True 
      TabControl1.SelectedTab = PageNew 

     End If 

    End Sub 


Private Sub BtnTab_Click(sender As Object, e As EventArgs) Handles BtnTab.Click 

     'Button is visible when TabPages are opened, and with click It closes selected TabPage 
     Me.TabControl1.TabPages.Remove(Me.TabControl1.SelectedTab) 

     'IF no TabPages, button hides again 
     If TabControl1.TabPages.Count = 0 Then 
      TabControl1.Visible = False 
      BtnTab.Visible = False 
     End If 
    End Sub 

Answer 1

對象已存在，只是隱藏的，你又創造它，重新創建對象之前的處理。

Dim tbp As TabPage = TabControl1.SelectedTab 
TabControl1.TabPages.Remove(tbp) 
tbp.Dispose()