You may need to set minimum Height/Width:
VB Code:
  1. Option Explicit

  2.  
  3. Dim iMinWidth As Integer

  4. Dim iMinHeight As Integer

  5.  
  6. Private Sub MDIForm_Load()

  7.     iMinWidth = 12000

  8.     iMinHeight = 8000

  9. End Sub

  10.  
  11. Private Sub MDIForm_Resize()

  12.     If Me.WindowState = vbNormal Then

  13.         If Me.Width < iMinWidth Then Me.Width = iMinWidth

  14.         If Me.Height < iMinHeight Then Me.Height = iMinHeight

  15.     End If

  16. End Sub