I wonder if I can let the modalPopupExtender's panel to be poped up after some C# code was executed?

Here my panel consist some textboxes and I need the data to be filled in before it was pop up.

I tried to set the modalPopupExtender to disabled first and enable it in C# code after the C# code was executed, but the panel won't pop up, only if I click the targetControlbutton again, the panel will pop up.

Any ideas?

You have to trick the modalpopup.  First, create an asp:button with css style display:none, so <asp:button id="hButton" runat="server" style="display:none;" />.  Dont use Visible=false because then it wont be rendered at all and the modalpopup wont be able to see it and youll get funky errors.  It has to be display:none;

then set that hidden button as the targetcontrol of the modalpopup.  Now you can just call .Show() and .Hide from code anywhere you want.

Eric

Thank you Eric! do you mean to call hButton.show() in C#?

No, call the modalpopupexter.show

Call modalpopupID.show()

No, in the codebehind call YourModalPopup.Show();

Thank you~! works great~~~!!!!