Compatiblity with Page Widgets and similar plugins
At the moment if you add an event calendar widget to a widget area from the post itself, using a plugin such as Page Widgets (http://wordpress.org/plugins/wp-page-widget/), the category selector doesn't work, because, not expecting to be loaded on the post edit screen, it doesn't load all its scripts.
This can be fixed if you want to make your plugin compatible, by modifying line 18 of /events-calendar-pro/lib/widget-calendar.class.php from
if ( $hook != ‘widgets.php’ )
if ( $hook != ‘widgets.php’ && $hook != ‘post.php’ )
Now everything works. I realise that if you were to implement this you’d want to either detect the Page Widgets plugin and add this line if it is found (so as not to load the scripts needlessly), or alternatively add a tick box in your options along the lines of “Enable Page Widgets compability”, which would add this bit. I'll leave that with you!
There's no reason not to queue the assets on other pages because scripts and styles are cached. Rather than adding compatibility for this one plugin, this should be viewed as a request to fix a bug that breaks built-in compatibility.