How to Hide the DropDownList Behind Layer
A very common problem for modern web interface developers is displaying layers over a DropDownListBox. The DropDownListBox always wants to be displayed on top of any other control or layer in the page. This is because the DropDownListBox is actually a system control and not something controlled by the browser.
Recently I came into a situation where I needed to display a layer as a Model dialog on top of my web page. The dialog layer would not hide a DropDownListBox that happened to be position directly behind it.
Hiding the DropDownListBox
Registering the Startup script is done in the code behind.IfMe.ClientScript.IsStartupScriptRegistered('ShowModalDialog') = FalseThenDim sb AsNew StringBuilder
sb.Append('document.all['ModalDialogLayer'].style.visibility = 'visible';document.all['PopUpBackGround'].style.height = 1500;document.all['PopUpBackGround'].style.width = window.screen.availWidth;document.all['PopUpBackGround'].style.visibility = 'visible';document.all['dlWrapperLayer'].style.visibility = 'hidden';')Me.ClientScript.RegisterStartupScript(GetType(printcopyfax), 'ShowModalDialog', sb.ToString, True)EndIf
I will try to remember to write an entry on doing a modal dialog soon, so don't worry.
Redisplay the DropDownListBox
I have a button on my dialog layer to close it, or essentially hide it from view. I leverage the onclick event handler to redisplay the drowdownlistbox.<inputid='cbDontShow'value='I Acknowledge'type='button'accesskey='S'title='Ackowledge Message.'runat='server'onclick='document.all['ModalDialogLayer'].style.visibility = 'hidden';document.all['dlWrapperLayer'].style.visibility = 'visible';document.all['PopUpBackGround'].style.visibility = 'hidden';'/></td>
Hopefully this will prove to be useful for you in the future.