VB.NET
* Imports System.Drawing.Color

Public Class Form1

Private Sub Button1_MouseMove(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Button1.MouseMove

Button1.BackColor = Blue
Button2.BackColor = Black
Button3.BackColor = Black
Button4.BackColor = Black
End Sub

Private Sub Button2_MouseMove(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Button2.MouseMove

Button1.BackColor = Black
Button2.BackColor = Green
Button3.BackColor = Black
Button4.BackColor = Black
End Sub

Private Sub Button3_MouseMove(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Button3.MouseMove

Button1.BackColor = Black
Button2.BackColor = Black
Button3.BackColor = Yellow
Button4.BackColor = Black
End Sub

Private Sub Button4_MouseMove(sender As Object, e As System.Windows.Forms.MouseEventArgs) Handles Button4.MouseMove

Button1.BackColor = Black
Button2.BackColor = Black
Button3.BackColor = Black
Button4.BackColor = Red
End Sub
End Class 

버튼 4개 필요.