Bookmarking clicked objects?

Rod has explained the situation in his usual elaborate and clarifying way. Hope you understand that the way you did set up the actions is important, if you want to use that approach with retrieving user variables. If you just used the 'Show' command, even in an advanced or shared action, tno user variables are in the workflow. Example: a toggle button to show/hide an object can be done with show/hide commands, or you can use a conditional action like this:

IF v_visib is equal to 0

    Show xxxx

    Toggle v_visib

ELSE

     Hide xxxx

     Toggle v_visib

That conditional action  which I use as shared action does implicate a user variable, which can be used for Rod's workflow.

It is possible, but it depends on whether or not your particular LMS will persist the values of User Variables in the Captivate content. 

Some LMSs will store the current value of User Variables when the learner closes the browser without reaching completion of the module.  So, if your course interaction was set up with a User Variable that recorded the current hidden or visible status of an object, and the ON Slide Enter event of that slide was set up to execute a Conditional Action that either shows or hides the object based on the value of this variable, THEN you might be on a winner.

However, not all LMSs will persist User Variables by default. If it turns out that yours is NOT set up to do this, then you would need to start investigating use of JavaScript programming to take advantage of other methods of persisting variables, perhaps using the Local Storage area of the web browser.  

For HTML5 e-learning you might also investigate use of data persistence functionality in the CpExtra HTML5 widget: http://www.infosemantics.com.au/adobe-captivate-widgets/cpextra/help/data-persistence  This achieves a similar result without requiring you to learn JavaScript.