Sitecore - Adding button to FormDialog

Question

Is it possible to add a custom button to a Sitecore FormDialog other than OkButton and CancelButton e.g. instead of this

<FormDialog Icon="cool.png" Header="A really cool header" Text="Link or un-link items" OKButton="Link" CancelButton="Close">

but something more like this

<FormDialog Icon="cool.png" Header="A really cool header" Text="Link or un-link items" OKButton="Link" UnLinkButton="UnLink" CancelButton="Close">

Answer 1

I don't think it is possible to add another button by passing in an attribute on the FormDialog element without modifying original the FormDialog.xml

But there is a placeholder element defined in the DialogForm control (in /sitecore/shell/Controls/Dialogs)

<def:Placeholder name="Buttons"/>

In the xml for your custom application you add controls to this placeholder:

<control xmlns:def="Definition" xmlns="http://schemas.sitecore.net/Visual-Studio-Intellisense">
  <MyCustomForm>
    <FormDialog Icon="cool.png" Header="A really cool header" Text="Link or un-link items" OKButton="Close" CancelButton="false">

      <CodeBeside Type="MyCustomCode.Dialogs.MyCustomForm, MyCustomCode"/>

      <GridPanel Columns="2" CellPadding="4" Width="100%" Height="100%">
          <!-- Panel code here -->
      </GridPanel>

      <Border def:placeholder="Buttons" runat="server" style="float:right;">
        <Button Header="Link" runat="server" Type="button" Click="Link_Click" />
        <Button Header="Unlink" runat="server" Type="button" Click="Unlink_Click" onclick="return confirm('Are you sure you want to unlink?');" />      
      </Border>

    </FormDialog>
  </MyCustomForm>
</control>

Note you want to pass in CancelButton="false" which hides the cancel button and set the OK button text to "Close". Handle your Link/Unlink button server actions in the code behind. I've styled the button group to float:right so they then site next to the Close button.