VB.NET

Question

我在打开表单的地方有 ToolStripMenu。表单在 TabControl 中打开，它位于 Split Container 的面板之一。我也在 Split 容器中放置了一个按钮，它会关闭所有选定的 TabPages（表单打开的地方）。问题是，当我在新 TabPage 中打开表单并通过此按钮关闭它时，表单不再打开。为什么？ ....这是我的代码：

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

该对象已经存在，只是隐藏了，而您又要创建它，请在重新创建之前销毁该对象。

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

VB.NET - TabControl 中的表单在关闭后未打开

VB.NET - Form in TabControl not opened after closing It

tabcontrol