Have not yet resolved the issue.
@Timo, sorry, not sure what you mean by "custom skin object", but I have a custom skin, with index.ascx and other skin-related views, resources etc. In index.ascx, if I put:
<% IF ... %> or <%=... %>
the page, where the skin is applied, reloads after doing drag-n-drop. Same for built-in skins.
I tried wrapping these constructions into UpdatePanels, but I don't feel that this is the right approach and won't cause side affects. Moreover UpdatePanel stops working if I have a ContentPane in it.
Would appreciate any ideas, suggestions, cause more and more people start using DNN9 and complaining of that reloads.