The Theme Installer displays an "Activate" button for the already active theme

[afercia]

Noticed while investigating on #50316.

In previous versions of WordPress, when navigating themes in the Theme Installer, the active theme displayed a visually disabled button (actually it's a href="#" link) with text "Installed". See first screenshot attached below.

Starting from WordPress 4.6, this button (actually still a link) is a working link with text "Activate", which doesn't make much sense as the displayed theme is already the active one. See second screenshot attached below.

Not sure if this change was intentional, but worth investigating. In any case, the "Activate" button/link is a bit misleading.

To reproduce:

• take note of the name of your currently active theme
• go to the Add Themes page, located at wp-admin/theme-install.php?browse=featured
• search for the name of your active theme
• in the search results, click on "Details & Preview" on your active theme
• the Theme Installer opens
• observe the button/link at the top of the left sidebar and see the text says "Activate"
• click the link
• the theme installer opens and a notice appears on the page with the message "New theme activated. Visit site"

[afercia]

WP 3.9 Theme Installer displays an "Installed" button for the Active theme

[afercia]

WP 4.6 Theme Installer displays an "Activate" button for the Active theme

[joyously]

Could this be a side effect of the change in the theme previewer, to remove the cookies?

[SergeyBiryukov]

Good catch, introduced in [37714].

[SergeyBiryukov]

In 47924:

Themes: Show a disabled "Activated" button instead of "Activate" for the active theme on Add Themes screen.

Additionally, switch the "Live Preview" label for the active theme to "Customize", for consistency with the Themes screen.

Props afercia, SergeyBiryukov.
Fixes #50334.

[SergeyBiryukov]

In 48037:

Themes: Ensure the theme slug is set before checking if the theme is installed or active.

This fixes an issue with every installed theme being marked as active on Themes screen.

The slug is set on Add Themes screen, but not on Themes.

Follow-up to [47924].

Props BackuPs, mukesh27, SergeyBiryukov.
Fixes #50381. See #50334.