Hi Michael,
just an idea. I would may be name the button "Task Done" or something. Then double click the button and click the "Edit Code"
button. Now use custom code to check if all your required fields are filled out correctly (e.g. field1 is a text box for which you want to test if it is filled or not)
if(XDocument.DOM.selectSingleNode(my:myFields/my:field1).text != "")
{
XDocument.View.SwitchView("viewName");
}
else
{
XDocument.UI.Alert("Your alert message");
}
Hope this helps