MS Access: Modal Dialogs with Transparent Backgrounds (redux)

Microsoft Access Team made an interesting post and a follow-up on how to add a transparent layer that cover the screen to focus the attention of the user to a login form or other important popup window.

The trick is to use some WIN 32 API calls to modify the transparency of a standard MS Access form made to cover the screen.

The effect is quite neat and I thought I would try it and make a sample database for others to tinker with it.
My version allows you to chose between covering the whole screen or just the main Access window and it will test if it’s running under a Remote Desktop Terminal and disable the layer in that case.

###Update 07MAY2008###
Following Rob’s improvements I made another sample database that incorporates his code with a few improvements:

* I added the LightBoxForm.LayerToFullScreen property so users can choose explicitly how they want the layer to be shown.
* I moved the code to hide the layer into a Hide() sub so you can just show/hide the layer using LightboxForm.Show and LightboxForm.Hide.
* I changed the Form’s Resize event code in the `LightBoxForm` class to avoid flickering: resizing the form within its `Resize` event actually trigger the `Resize` event again a second time which causes flickering.
I simply modified the code to make the form totally transparent (opacity of 0) the first time the event is fired and assign it the expected opacity when the event handler in re-entered.

~~~~brush:vb
‘—————————————————————————–
‘ Handle the Layer Form Resize event
‘—————————————————————————–
Private Sub m_objForm_Resize()
Static busyResizing As Boolean
Dim lngStyle As Long
Dim r As RECT

‘ disable screen updates
m_objForm.Painting = False

‘ When the form opens initially, we make it totally transparent to avoid flickering
lngStyle = GetWindowLong(m_objForm.hWnd, GWL_EXSTYLE)
SetWindowLong m_objForm.hWnd, GWL_EXSTYLE, lngStyle Or WS_EX_LAYERED
SetLayeredWindowAttributes m_objForm.hWnd, 0, 0, LWA_ALPHA

‘ If the Access window is maximized, then maximize the lightbox form.
‘ If the Access window is not maximized, then
‘ position the lightbox form so that it covers the Access window
If IsZoomed(hWndAccessApp()) Or m_bLayerToFullScreen Then
DoCmd.Maximize
Else
GetWindowRect Application.hWndAccessApp(), r
MoveWindow m_objForm.hWnd, r.x1, r.y1, (r.x2 – r.x1), (r.y2 – r.y1), True
End If

If busyResizing Then
‘ Get the current window style, then set transparency
lngStyle = GetWindowLong(m_objForm.hWnd, GWL_EXSTYLE)
SetWindowLong m_objForm.hWnd, GWL_EXSTYLE, lngStyle Or WS_EX_LAYERED
SetLayeredWindowAttributes m_objForm.hWnd, 0, (m_sngOpacity * 255), LWA_ALPHA
‘ enable screen updates
m_objForm.Painting = True
‘ Back to normal
busyResizing = False
Else
busyResizing = True
End If
End Sub
~~~~

###Samples###
There are now 2 sample databases. Ech zip contains a Microsoft Access 2007 ACCDB file and its conversion to Access 2000[^1] and Access 2002-2003 MDB but please note that I have not been been able to test those in older version of Access and that form transparency doesn’t work in Operating Systems older than Windows 2000.

Download TransparentLayer02b.zip (138KB), recommended version
(improved, more flexible version, based on Rob’s updated article).

Download TransparentLayer01b.zip (122KB), original version
(simple code, based Rob’s original article).

###Troubleshooting###
* _If you are getting security warnings:_ make sure that you open the database from a Trusted Location or you will receive a security prompt.
If you don’t know how to do that, check these steps.
* _If the layer appears on top of the login form instead of behind:_ make sure that the top-most form has ist Modal properties set to `Yes` and the `frmLightBox` form has its modal property set to `No`.
If you improve on it, please let me know and I’ll post it here for all to find.

[^1]: A specific version for Access 2000 now included in the archive (updated 25JUL2008).