Hi Floris246,
The Rich TextEditor default toolbar is "ribbon", so please open file "\richtexteditor\scripts\config.js", find the ribbon toolbar defind section below
- "ribbon": "<@COMMON,ribbonpaste,pastetext,pasteword,{save,new,print,spellcheck}{cut,copy,delete,find}{undo,redo|formatpainter}><@FORMAT,[fontname,fontsize]{bold,italic,underlinemenu|forecolor,backcolor}{superscript,subscript,changecase|removeformat,cleancode,selectall}><@PARAGRAPHS,[paragraphs,styles]{justifymenu,lineheight,ltr,rtl,insertlinemenu}{insertorderedlist,insertunorderedlist,outdent,indent,insertblockquote}><@INSERT,ribbontable,insertgallery,insertimage,{insertform,insertbox,insertlayer,insertfieldset,fullscreen,toggleborder,pageproperties,help}{insertlink,unlink,insertanchor,insertimagemap,insertdate,insertchars,virtualkeyboard}{inserttemplate,insertdocument,insertvideo,syntaxhighlighter,insertyoutube,html5,googlemap}>",
And add your custom button name for this section
"ribbon": "<@COMMON,ribbonpaste,pastetext,pasteword,{save,new,print,spellcheck}{cut,copy,delete,find}{undo,redo|formatpainter}><@FORMAT,[fontname,fontsize]{bold,italic,underlinemenu|forecolor,backcolor}{superscript,subscript,changecase|removeformat,cleancode,selectall}><@PARAGRAPHS,[paragraphs,styles]{justifymenu,lineheight,ltr,rtl,insertlinemenu}{insertorderedlist,insertunorderedlist,outdent,indent,insertblockquote}><@INSERT,ribbontable,insertgallery,insertimage,{insertform,insertbox,insertlayer,insertfieldset,fullscreen,toggleborder,pageproperties,help}{insertlink,unlink,insertanchor,insertimagemap,insertdate,insertchars,virtualkeyboard}{inserttemplate,insertdocument,insertvideo,syntaxhighlighter,insertyoutube,html5,googlemap,mybutton1}>",
Regards,
Ken