Yeah, there were a couple of ways that seem to fix this issue. Some of these are more viable than others.
1. Don't use RadFormDecorator with RenderMode="Classic". This means either removing the RadFormDecorator or changing it's render mode. Either of these can have ramifications on your site. I don't know what the default render mode is, when none is specified.
2. Convert your checkboxes and radio buttons (yes i found examples where the same behavior occurs w/ radio buttons after i posted the original issue) to RadButtons. This is pretty straightfoward
<
asp:checkbox
id
=
"chk1"
runat
=
"server"
text
=
"Checkbox 1"
value
=
"1"
/>
becomes
<
telerik:radbutton
id
=
"chk1"
runat
=
"server"
Text
=
"Checkbox 1"
value
=
"1"
ButtonType
=
"ToggleButton"
,
ToggleType
=
"Checkbox"
causesvalidation
=
"false"
autopostback
=
"false"
Skin
=
"Default"
/>
and to make a RadioButton you simply change
ToggleType="CheckBox" to ToggleType="RadioButton" GroupName="somevalue"
the conversion is mostly straightforward. it gets tricky if you have CheckBoxList or RadioButtonList controls as each needs to become it's own button with it's own unique ID, and sometimes if you have client-side events its a little tricky because the client libraries are a little different. but otherwise you can treat the button just like class checkbox or radio button.
This was the approach i went with to fix my site, converting all offenders to Radbuttons. I specified the skin="Default" so that they looked as much as possible like classic versions of the controls they replaced.
Telerik we're really hoping for you to weigh in on this issue. If you'd rather me post a support ticket i'm happy to do so.
-Mark