Update body-toolbar-button - use value={{{ [subfilter{!!button-classes}] :and[join[ ]] }}} (#9585)

* Update body-toolbar-button - use `filter={{!!button-classes}}`

* Update body-toolbar-button.tid

* Create #9566 - button-classes.tid

* Update and rename #9566 - button-classes.tid to #9585 - button-classes.tid

* :and[join[ ]]

* Update how-to guide to mention button-classes

core/ui/EditTemplate/body-toolbar-button.tid

@@ -103,9 +103,9 @@ title: $:/core/ui/EditTemplate/body/toolbar/button
 <$set
 
   name="buttonClasses"
-  value={{!!button-classes}}
+  value={{{ [subfilter{!!button-classes}] :and[join[ ]] }}}
 
 ><<toolbar-button>></$set>
 \end
 
-<<toolbar-button-outer>>
+<<toolbar-button-outer>>

editions/tw5.com/tiddlers/howtos/How to create dynamic editor toolbar buttons.tid

@@ -1,5 +1,5 @@
 created: 20201216182347597
-modified: 20211018102328148
+modified: 20260206104319886
 tags: 
 title: How to create dynamic editor toolbar buttons
 type: text/vnd.tiddlywiki
@@ -91,6 +91,9 @@ This tiddler contains all the necessary elements that are important for toolbar
 ; shortcuts
 : This is the [[Keyboard Shortcut Descriptor]] eg: `((temp-bold))`
 
+; button-classes <<.from-version "5.4.0">>
+: Additional CSS classes applied to the created button, definable as a list or filter expression
+
 <<<
 
 !! Disabled State

editions/tw5.com/tiddlers/releasenotes/5.4.0/#9585 - button-classes.tid

@@ -0,0 +1,13 @@
+title: $:/changenotes/5.4.0/#9585
+created: 20260106174849522
+modified: 20260106174849522
+tags: $:/tags/ChangeNote
+change-type: enhancement
+change-category: usability
+description: The button classes of Editor toolbar buttons can now be evaluated as filter expressions
+release: 5.4.0
+github-links: https://github.com/TiddlyWiki/TiddlyWiki5/pull/9585
+github-contributors: BurningTreeC
+type: text/vnd.tiddlywiki
+
+This change lets you define the button-classes of Editor toolbar buttons as filters for flexible styling