Sorry, I misunderstood your question originally (because I didn’t remember that the sync functions had buttons on the toolbar, so my mind immediately went to the CustomizeToolbar plugin, instead of thinking of the built-in toolbarIcons feature).

In v8.4.2-v8.4.9, Notepad++ was not correctly tracking whether horizontal/vertical synchronization was possible, so it wasn’t changing those icons, and thus, it always used your custom sync-vertical.ico and sync-horizontal.ico

However, in v8.5, Notepad++ fixed that tracking and started using an enabled and disabled version of the builtin icon, but the developer apparently didn’t think about adding the ability to have sync-vertical_disabled.ico and sync-horizontal_disabled.ico – so when the sync are enabled, they use your custom icon, but when sync is disabled, it defaults to using the builtin icon.

In order for it to be implemented to look for sync-vertical_disabled.ico and sync-horizontal_disabled.ico when the sync is disabled, someone would have to create an official feature request (as described in our FAQ), and then the developer or one of the other volunteers would have to implement that feature. If you do submit such a request, please paste a link to the request in a reply here, so that other interested people can follow the status of the request.

I am not making a bar based on a plugin. Instead, I am creating a custom toolbar according to the official notepad++ documentation given at this address: https://github.com/notepad-plus-plus/npp-usermanual/blob/master/content/docs/config-files.md#toolbar-icon-customization-toolbariconsxml

It can be tested by downloading the official ‘old big legacy icons’ from here: https://notepad-plus-plus.org/assets/data/nppLegacyIconSet.zip
or by using this custom toolbar: https://community.notepad-plus-plus.org/topic/23090/toolbar-fugue-icons-for-notepad

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I have been doing several tests downloading different versions of np++, up to version 8.4.9 they work correctly, they mark the status of pressed or not when you click on them, then it would not be necessary to add extra icons for when they are disabled.

From version 8.5.0 onwards, the custom icons for the functions ‘Synchronize vertical scrolling’ and ‘Synchronize horizontal scrolling’ are not displayed.

Are you using the CustomizeToolbar plugin for “creating a button bar with custom icons”. As far as I know, that plugin doesn’t currently have the capability to have separate icons for “enabled” vs “disabled”. The author of the plugin, @dave-user, hasn’t visited the forum in more than two years. In theory, that plugin has a feature requests section, but I’m not sure it’s ever been actively tracked; there is more activity in the plugins “Help” discussion area, but even that, I don’t see any activity by the author in 2+ years.

Or are you creating your own plugin, and creating a new toolbar beyond Notepad++'s normal toolbar? In that case, any such logic is really up to you as the author of the plugin.

But either way, there’s nothing Notepad++ itself can do, because Notepad++ alone doesn’t deal with custom toolbar buttons.