Anpassen der Titelzeile einer WinForms-Form

    
Imports System.Runtime.InteropServices
Public Class FormTest
                    Inherits Form

<DllImport("user32.dll", SetLastError:=True)>  
    Private Shared Function SetWindowCompositionAttribute(hWnd As IntPtr, ByRef data As WindowCompositionAttributeData) As Integer
    End Function

    <StructLayout(LayoutKind.Sequential)>
    Private Structure AccentPolicy
        Public nAccentState As Integer
        Public nFlags As Integer
        Public nColor As Integer
        Public nAnimationId As Integer
    End Structure

    <StructLayout(LayoutKind.Sequential)>
    Private Structure WindowCompositionAttributeData
        Public Attribute As Integer
        Public Data As IntPtr
        Public SizeOfData As Integer
    End Structure

    Private Const WCA_ACCENT_POLICY As Integer = 19
    Private Const ACCENT_ENABLE_BLURBEHIND As Integer = 3

    Public Sub New()
        InitializeComponent()
        SetTitleBarColor(Color.FromArgb(1, 93, 109)) ' Aufruf der Funktion, um die Farbe der Titelleiste zu ändern  
    End Sub

    Private Sub SetTitleBarColor(color As Color)
        Dim accent As New AccentPolicy()
        Dim accentStructSize As Integer = Marshal.SizeOf(accent)
        accent.nAccentState = ACCENT_ENABLE_BLURBEHIND
        accent.nFlags = 2
        accent.nColor = ColorToABGR(color)

        Dim accentPtr As IntPtr = Marshal.AllocHGlobal(accentStructSize)
        Marshal.StructureToPtr(accent, accentPtr, False)

        Dim data As New WindowCompositionAttributeData()
        data.Attribute = WCA_ACCENT_POLICY
        data.SizeOfData = accentStructSize
        data.Data = accentPtr

        Dim hWnd As IntPtr = Me.Handle
        SetWindowCompositionAttribute(hWnd, data)

        Marshal.FreeHGlobal(accentPtr)
    End Sub

    Private Function ColorToABGR(color As Color) As Integer
        Return (CInt(color.A) << 24) Or (CInt(color.B) << 16) Or (CInt(color.G) << 8) Or CInt(color.R)
    End Function

End Class