解决GridView MouseLeave重复触发：点击外部仅执行一次指令

为什么MouseLeave会频繁触发？ #

GridView内部包含大量子控件（如单元格、滚动条、表头），当鼠标从GridView主体移到这些子控件上时，也会触发GridView的MouseLeave事件，导致你的代码被重复执行。

方案1：用标志位+子控件MouseEnter联动控制 #

通过一个布尔变量标记鼠标是否真正离开整个GridView区域，同时绑定所有子控件的MouseEnter事件，确保鼠标在GridView内部移动时不会误触发逻辑：

1. 先声明全局标志变量：

Private isGridViewHovered As Boolean = False

2. 绑定GridView及其子控件的MouseEnter事件：

Private Sub GridView2_MouseEnter(sender As Object, e As EventArgs) Handles GridView2.MouseEnter
    isGridViewHovered = True
End Sub

Private Sub Form_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    ' 递归绑定所有子控件的MouseEnter
    BindChildMouseEnter(GridView2)
End Sub

Private Sub BindChildMouseEnter(control As Control)
    For Each child As Control In control.Controls
        AddHandler child.MouseEnter, AddressOf GridView2_MouseEnter
        BindChildMouseEnter(child)
    Next
End Sub

3. 修改MouseLeave事件，通过标志位控制仅执行一次：

Private Sub GridView2_MouseLeave(sender As Object, e As EventArgs) Handles GridView2.MouseLeave
    If isGridViewHovered Then
        ComboBox55.Text = "A"
        ComboBox44.Text = "B"
        ComboBox13.Text = "NO"
        NumericUpDown14.Value = 0
        ToggleSwitch34.IsOn = False
        isGridViewHovered = False
    End If
End Sub

方案2：直接监听窗体点击事件（更贴合你的需求） #

你的核心需求是点击GridView外部时触发操作，而非单纯的鼠标离开，所以直接监听窗体的MouseDown事件，判断点击位置是否在GridView之外：

Private Sub Form_MouseDown(sender As Object, e As MouseEventArgs) Handles MyBase.MouseDown
    ' 将鼠标点击的屏幕坐标转换为GridView的客户端坐标
    Dim gridPoint As Point = GridView2.PointToClient(e.Location)
    ' 判断点击点是否不在GridView的可视区域内
    If Not GridView2.ClientRectangle.Contains(gridPoint) Then
        ComboBox55.Text = "A"
        ComboBox44.Text = "B"
        ComboBox13.Text = "NO"
        NumericUpDown14.Value = 0
        ToggleSwitch34.IsOn = False
    End If
End Sub

这个方案更精准匹配你的需求，不会出现鼠标在GridView内部移动时误触发的问题。

内容的提问来源于stack exchange，提问作者LARC