You mention having possibility for plugins to define new 'view types'. I think this would be doable by adding a hook in the viewdatatable factory for example, and having the datatatable footers load the new icon, translations, etc.

Adding a hook in the viewdatatable would at least make it easier to add new views to the current datatable.

But I also thought about going one step further. The viewdatatable introduces a nice icon footer into many widgets used in Piwik. By now, this icon footer is not very reusable. In fact, if someone is going to write completely new multi-view widgets that integrate well in the current Piwik UI he would have to rebuild the icon footer by hand (including html setup and js functionality like auto-hide and last-view-saving). This is what I did while creating the map widget.

So my idea was to move the multi-view code from the viewdatatable to the Piwik core in a way that every new widget can easily create new views.

Another option would be to create an abstract multi-view widget which would be extended by the viewdatatable or any other new multi-view widgets. However, the UI logic for the icon footer should use a single codebase.

Unfortunately I have no time to do this myself, but here's the general idea:

you need to modify plugins/CoreHome/templates/datable_footer.tpl to somehow include custom icons (maybe another if, for example if $properties.customicons with a foreach), specifically the section {if $properties.show_all_views_icons}. The format attribute of <a> is the one passed over GET and recognized by ViewDataTable::factory, the var attribute tells the javascript which button to display when the icons are grouped and this one is selected.

You then need to modify ViewDataTable::factory to maybe check if the class passed over GET exists, if yes return a new object of that class, else revert to default. Also a new method to add custom icons is required, it would set $this->viewProperties['customicons'] to an array of the specified icons.

Your plug-in class (the one returned by ViewDataTable::factory) needs to have one method

protected function getViewDataTableId()
{
   return 'something';
}

where something is the same string as in the var attribute of <a> in datable_footer.tpl

I think that's all you need to do, but I'm not sure.

I agree with the concept, but you worked around nicely in #1558.

I don't think we will be adding this feature at this stage. Let's reopen the ticket if need be :)