Yes Vasiliy , It is possible to do that, You just have to define the tab structure in Custom-Action.xml properly.
- Define command like this and then
<command class="netmarkets" method="servlet/Navigation?tab='tab_id" windowType="page"/>
Define sub tabs as above, method name should be trailed by 'tab='tab_id' for each sub tab action.
- And in Custom-Action-Model.xml define navigation structure like
<model name="tab-id navigation" >
<description>Sub tabs under main tab</description>
<!-- <action name="" type=" "/> -->
<action name="" type=" "/>
<action name="" type=" "/>
<action name=" " type=" "/>
</model>
- Make sure you are defining the entries in RBInfo file and doing resource build after these changes.