Hiii,
I have master page where I have declared modalpopup extender and the same i want to use in the content page on any button click to show message.
In a Every content page i have used Update Panel.
<asp:ScriptManager ID="Manager1" runat="server"></asp:ScriptManager>
<!---MessageBox Modal Popup-->
<%-- <asp:UpdatePanel runat="server">
<ContentTemplate>--%>
<asp:Panel ID="pnlMessageAlert" runat="server" Style="display: none;">
<div class="alert alert-success" role="alert" runat="server" id="AlertMsg">
<asp:LinkButton ID="btnCloseAlert" runat="server" CssClass="close" data-dismiss="alert" aria-label="Close"><span aria-hidden="true">×</span></asp:LinkButton>
<span class=" glyphicon glyphicon-ok"></span> <strong>Alert!</strong>
<asp:Label ID="lblmsg" runat="server" Text=""></asp:Label>
</div>
</asp:Panel>
<%-- </ContentTemplate>
</asp:UpdatePanel>--%>
<asp:LinkButton ID="lnkFakeAlert" runat="server"></asp:LinkButton>
<cc1:ModalPopupExtender ID="mpeMessageBox" runat="server" PopupControlID="pnlMessageAlert"
TargetControlID="lnkFakeAlert" BehaviorID="mpeMessageAlert" CancelControlID="btnCloseAlert"
BackgroundCssClass="modalBackground">
</cc1:ModalPopupExtender>
<!---MessageBox Modal Popup End-->
<div class="x_content">
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
</asp:ContentPlaceHolder>
</div>
Below is the Content Page Code .
<asp:UpdatePanel ID="upPanelMain" runat="server">
<ContentTemplate>
<div class="form-horizontal ">
<div class="form-group">
<div class="col-md-2 col-lg-2 col-sm-12 col-xs-12">
<asp:LinkButton ID="btnClear" runat="server" CssClass="btn btn-success btn-block" OnClick="btnClear_Click"><span class="fa fa-repeat"></span> Clear</asp:LinkButton>
</div>
</div>
</div>
</ContentTemplate>
</asp:UpdatePanel>
protected void btnClear_Click(object sender, EventArgs e)
{
ModalPopupExtender mpeMessageBox = this.Master.FindControl("mpeMessageBox") as ModalPopupExtender;
mpeMessageBox.Show();
//((ModalPopupExtender)this.Parent.Parent.FindControl("mpeMessageBox")).Show();
}