Option Explicit

Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private MouseDownForm
Private MouseDownFormX
Private MouseDownFormY
Private Type POINTAPI
     X As Long
     Y As Long
End Type


Private Sub form_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
MouseDownForm = 1
MouseDownFormX = X
MouseDownFormY = Y
End Sub

Private Sub form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
MouseDownForm = 0
End Sub

Private Sub form_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
If MouseDownForm <> 1 Then
Exit Sub
End If
Dim Z As POINTAPI
Call GetCursorPos(Z)
frmMain.Top = (Z.Y * 15) - MouseDownFormY
frmMain.Left = (Z.X * 15) - MouseDownFormX
End Sub

Option Explicit

Private Declare Function SendMessage _
                Lib "user32" _
                Alias "SendMessageA" (ByVal hWnd As Long, _
                                      ByVal wMsg As Long, _
                                      ByVal wParam As Long, _
                                      lParam As Any) As Long
                                      
Private Declare Function ReleaseCapture _
                Lib "user32" () As Long
                
Private Const WM_NCLBUTTONDOWN = &HA1
Private Const HTCAPTION = 2

Private Sub Form_MouseDown(Button As Integer, _
                           Shift As Integer, _
                           X As Single, _
                           Y As Single)
    If Button = 1 Then
        ReleaseCapture
        Call SendMessage(Me.hWnd, WM_NCLBUTTONDOWN, HTCAPTION, 0)
    End If
End Sub