Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim mdi As New Form2
        Dim a As New Form2
        mdi.MdiParent = Me
        mdi.Show()
End Sub
这个每次单击一次都弹出窗体,而且不能关闭.
我想实现单击第一次弹出窗体,在同一个按钮下单击第二次则关闭这个刚弹出的窗体。
该怎么改呢？？
谢谢！

参考以下代码，是否可以满足你的要求？
Public Class Form1
    Dim fShow As Boolean = False '先声明一个变量
    Dim mdi As New Form2

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        mdi.MdiParent = Me
        If fShow Then
            fShow = False
            mdi.Hide()
        Else
            fShow = True
            mdi.Show()
            mdi.Top = 0
            mdi.Left = 0
        End If
    End Sub
End Class

谢谢。但是，单击弹出的窗口,点右上角的关闭后，再点按钮打开窗口时就弹不出来了。

我也学习一下

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If Form2.Created = True Then
            Form2.Close()
        Else
            Form2.Show()
        End If
    End Sub
用此方法吧,应没问题

回复3楼：如果只有一个子窗体，尝试下面的代码。

Public Class Form1
    Dim fShow As Boolean = True '先声明一个变量
    Dim mdi As Form2

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If Me.MdiChildren.Length = 0 Then
            mdi = New Form2
            mdi.MdiParent = Me
            mdi.Show()
            mdi.Top = 0
            mdi.Left = 0
            Return
        End If
        mdi.MdiParent = Me
        If fShow Then
            fShow = False
            mdi.Hide()
        Else
            fShow = True
            mdi.Show()
            mdi.Top = 0
            mdi.Left = 0
        End If
    End Sub
End Class


[ 本帖最后由 sywzs 于 2010-3-4 08:46 编辑 ]