I want to create a Dialog in CRM to show some sort of greeting message on user logon. But I didn't find out how to assign Dialogs and Workflows on events, how to make or bind event triggers on them?
Sultan
As far as I know, you can only implement dialogs on forms and I don't think it would be a great option for doing this.
The best bet for a greeting upon login is to modify the sitemap to load a custom web application as the default web page (or in 2011 add a iframe or html web resource to a dashboard). On this page you could pull information from CRM to display a greeting. Announcements is the typical place where these greetings are stored but you could create a custom entity to store them as well.