enable Customize Manager Theme-Preview to switch to the dedicated page of a control

[nimo24]

According to ​https://developer.wordpress.org/themes/customize-api/tools-for-improved-user-experience/ we can "Hide core sections/controls when they aren't used on the current page.".

However, actually the opposite is not possible: To show the dedicated page for sections/controls which are dedicated to that page and not to the actually shown page.

For example, at the beginning "page1" is shown, when clicking the "panel/section/control" which are dedicated to "page2", the theme customizer should switch to "page2" (unload "page1" and instead load "page2" within the iframe) to enable live preview for that page, because the user selects a "panel/section/control" which is dedicated to "page2".

[celloexpressions]

This is currently possible via the JS API, and should probably remain in JS rather than PHP since it can happen much more directly that way. There are a couple of core examples for this, such as the "original" link in menu item controls and the front page and posts page controls.

I've added a new section with an example of this to the documentation on the JS API: ​https://developer.wordpress.org/themes/customize-api/the-customizer-javascript-api/#preview-js-and-controls-js. In your particular case, you'll want to bind a callback to the section's expanded state and change the preview URL when it turns true.

[michal88sla]

nead image created by Michal Marciniak