Buttons link issue when drupal is in subdirectory

Problem/Motivation

Using Drupal in a subdirectory, the buttons in the views as "List calendars" o "Add event" "Import Events from All Calendars" do not link properly to the url_base of the site.

Steps to reproduce

install Drupal in a subdirectory eg http://my.site/drupal
uncomment the line in .htaccess
RewriteBase /drupal

after installing and configuring the module, add a calendar, try to list all the events of the calendar
http://my.site/drupal/calendar/1/events
at the top of the view (/admin/structure/views/view/gcs_calendar_events/) there are two buttons
Button -> Add Events -- link to http://my.site/calendar/1/event/add ERROR! it should be http://my.site/drupal/calendar/1/event/add
Button -> Import Events -- link to http://my.site/calendar/1/import?destination=/calendar/1/events ERROR! it should be http://my.site/drupal/calendar/1/import?destination=/calendar/1/events

Same error in the buttons of the Google Calendar Events view page:

Button -> List Calendars -- http://my.site/calendar ERROR! should link to http://my.site/drupal/calendar
Button -> Import Events from All Calendars -- http://my.site/calendar/all/import ERROR! should be http://my.site/drupal/calendar/all/import

Proposed resolution

modify the path

Remaining tasks

User interface changes

API changes

Data model changes