Great question! The issue you're facing is that when your main form is minimized with ShowInTaskbar = False, Windows stops sending the WM_HOTKEY messages to your main form's message queue—since the form isn't visible in the taskbar, the system doesn't prioritize it as a target for global hotkey events.

The most reliable fix is to use a hidden auxiliary window to handle hotkey registration and message processing. This window runs in the background permanently (until your app exits) and will receive hotkey events regardless of your main form's state. Here's how to implement it step-by-step:

Step 1: Create a Hidden Hotkey Handler Form #

Add a new Windows Form to your project (name it HotkeyHandlerForm), then set these properties in the designer:

• Visible = False
• ShowInTaskbar = False
• FormBorderStyle = FormBorderStyle.None

This ensures the form is completely invisible and won't interfere with your app's UI.

Step 2: Implement Hotkey Logic in the Auxiliary Form #

Replace the code in HotkeyHandlerForm.vb with this:

Public Class HotkeyHandlerForm
    ' P/Invoke declarations for hotkey functions
    Public Declare Function RegisterHotKey Lib "user32" (ByVal hwnd As IntPtr, ByVal id As Integer, ByVal fsModifiers As Integer, ByVal vk As Integer) As Integer
    Public Declare Function UnregisterHotKey Lib "user32" (ByVal hwnd As IntPtr, ByVal id As Integer) As Integer
    Public Const WM_HOTKEY As Integer = &H312

    ' Key modifier enum
    Private Enum KeyModifier
        None = 0
        Alt = &H1
        Control = &H2
        Shift = &H4
        Winkey = &H8
    End Enum

    ' Event to notify the main form when a hotkey is pressed
    Public Event HotKeyPressed(ByVal hotkeyId As Integer)

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        ' Handle hotkey messages
        If m.Msg = WM_HOTKEY Then
            RaiseEvent HotKeyPressed(m.WParam.ToInt32())
        End If
        MyBase.WndProc(m)
    End Sub

    Private Sub HotkeyHandlerForm_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' Register your hotkeys
        RegisterHotKey(Me.Handle, 1001, KeyModifier.Alt, Keys.F1)
        RegisterHotKey(Me.Handle, 1002, KeyModifier.Alt, Keys.F2)
        RegisterHotKey(Me.Handle, 1003, KeyModifier.Alt, Keys.F3)
        RegisterHotKey(Me.Handle, 1004, KeyModifier.Alt, Keys.F4)

        ' Optional: Check if registration succeeded
        ' If RegisterHotKey(Me.Handle, 1001, KeyModifier.Alt, Keys.F1) = 0 Then
        '     MessageBox.Show("Alt+F1 hotkey is already in use by another app!")
        ' End If
    End Sub

    Private Sub HotkeyHandlerForm_FormClosed(sender As Object, e As FormClosedEventArgs) Handles MyBase.FormClosed
        ' Unregister hotkeys when the form closes
        UnregisterHotKey(Me.Handle, 1001)
        UnregisterHotKey(Me.Handle, 1002)
        UnregisterHotKey(Me.Handle, 1003)
        UnregisterHotKey(Me.Handle, 1004)
    End Sub
End Class

Step 3: Update Your Main Form Code #

Modify your main form (FrmMain) to initialize the auxiliary form and handle hotkey events:

1. Add a global variable for the hotkey handler:

Private hotkeyHandler As HotkeyHandlerForm

2. Update the Load event to start the handler and subscribe to its event:

Private Sub FrmClient_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    NotifyIcon1.Text = Me.Text

    ' Initialize and show the hidden hotkey handler form
    hotkeyHandler = New HotkeyHandlerForm()
    AddHandler hotkeyHandler.HotKeyPressed, AddressOf OnHotKeyPressed
    hotkeyHandler.Show()
End Sub

3. Add a method to handle hotkey presses and trigger your buttons:

Private Sub OnHotKeyPressed(ByVal hotkeyId As Integer)
    Select Case hotkeyId
        Case 1001
            btnFunction1.PerformClick()
        Case 1002
            btnFunction2.PerformClick()
        Case 1003
            btnFunction3.PerformClick()
        Case 1004
            btnFunction4.PerformClick()
    End Select
End Sub

4. Update the Closed event to clean up the auxiliary form:

Private Sub FrmMain_Closed(sender As Object, e As EventArgs) Handles Me.Closed
    If hotkeyHandler IsNot Nothing Then
        hotkeyHandler.Close()
    End If
End Sub

5. Remove the old hotkey code from your main form:
   • Delete the RegisterHotKey/UnregisterHotKey declarations
   • Remove the WM_HOTKEY constant and KeyModifier enum
   • Delete the WndProc override that handled hotkeys

Why This Works #

The hidden auxiliary form maintains a valid window handle and active message loop at all times, so Windows will always send WM_HOTKEY messages to it—even when your main form is minimized or hidden from the taskbar. The form then raises an event that your main form listens to, triggering your button clicks as expected.

内容的提问来源于stack exchange，提问作者Christian Jay Soyosa