Private Sub Text1_Change()

Dim s As String, l As Long
s = Text1.Text
If Len(s) > 0 Then
For l = 1 To Len(s)
If Asc(Mid(s, l, 1)) < 48 Or Asc(Mid(s, l, 1)) > 57 Then
MsgBox "error"
Text1.Text = ""
Exit Sub
End If
Next l
End If

End Sub

Private Sub Form_Paint()
Dim X As Integer, Y As Integer
Dim ImgWidth As Integer
Dim ImgHeight As Integer
Dim FrmWidth As Integer
Dim FrmHeight As Integer

'использование Image1 в PaintPicture methods:
ImgWidth = Image1.Width
ImgHeight = Image1.Height
FrmWidth = Form1.Width
FrmHeight = Form1.Height

'залить целую форму (Метод 1)
For X = 0 To FrmWidth Step ImgWidth
For Y = 0 To FrmHeight Step ImgHeight
PaintPicture Image1, X, Y
Next Y
Next X

'залить левый край (Метод 2)
'For Y = 0 To FrmHeight Step ImgHeight
'PaintPicture Image1, 0, Y
'Next Y

End Sub

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 Sub ReleaseCapture Lib "User32" ()
Private Const WM_NCLBUTTONDOWN = &HA1
Private Const HTCAPTION = 2

Private Sub Image1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
Dim ReturnValue As Long
If Button = 1 Then
Call ReleaseCapture
ReturnValue = SendMessage(Me.hwnd, WM_NCLBUTTONDOWN, HTCAPTION, 0&)
End If
End Sub

Private Declare Function ChangeDisplaySettings Lib "user32" Alias "ChangeDisplaySettingsA" (lpDevMode As Any, ByVal dwflags As Long) As Long
Private Declare Function EnumDisplaySettings Lib "user32" Alias "EnumDisplaySettingsA" (ByVal lpszDeviceName As Long, ByVal iModeNum As Long, lpDevMode As Any) As Boolean
Const DM_PELSWIDTH = &H80000
Const DM_PELSHEIGHT = &H100000
Const CCFORMNAME = 32
Const CCDEVICENAME = 32
Private Type DEVMODE
dmDeviceName As String * CCDEVICENAME
dmSpecVersion As Integer
dmDriverVersion As Integer
dmSize As Integer
dmDriverExtra As Integer
dmFields As Long
dmOrientation As Integer
dmPaperSize As Integer
dmPaperLength As Integer
dmPaperWidth As Integer
dmScale As Integer
dmCopies As Integer
dmDefaultSource As Integer
dmPrintQuality As Integer
dmColor As Integer
dmDuplex As Integer
dmYResolution As Integer
dmTTOption As Integer
dmCollate As Integer
dmFormName As String * CCFORMNAME
dmUnusedPadding As Integer
dmBitsPerPel As Integer
dmPelsWidth As Long
dmPelsHeight As Long
dmDisplayFlags As Long
dmDisplayFrequency As Long
End Type
Public Sub ChangeResolution(iWidth As Single, iHeight As Single)
Dim DevM As DEVMODE
Dim a As Boolean
Dim i As Long
Dim b As Long
i = 0
Do
a = EnumDisplaySettings(0&, i&, DevM)
i = i + 1
Loop Until (a = False)
DevM.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT
DevM.dmPelsWidth = iWidth
DevM.dmPelsHeight = iHeight
b = ChangeDisplaySettings(DevM, 0)
End Sub

Private Sub Command1_Click()
ChangeResolution 640, 480 'Задавати можна любий розмір
End Sub