Hi @Justin_H , @EricShulman ,
excellent, exactly what I was looking for.
Maybe it would be a good idea to change the code of the “hamburger icon” to toggle from left, right and off mode for the sidebar. Only an idea 
What I was able to to was to add another icon to the menu and to change the chevrons to hide and show the side bar
\whitespace trim
<$list filter="[[$:/state/sidebar]get[text]] +[else[yes]!match[no]]" variable="ignore">
<$button set="$:/state/sidebar" setTo="no" tooltip={{$:/language/Buttons/HideSideBar/Hint}} aria-label={{$:/language/Buttons/HideSideBar/Caption}} class="tc-btn-invisible tc-hide-sidebar-btn">{{$:/core/images/chevron-up}}</$button>
</$list>
<$list filter="[[$:/state/sidebar]get[text]] +[else[yes]match[no]]" variable="ignore">
<$button set="$:/state/sidebar" setTo="yes" tooltip={{$:/language/Buttons/ShowSideBar/Hint}} aria-label={{$:/language/Buttons/ShowSideBar/Caption}} class="tc-btn-invisible tc-show-sidebar-btn">{{$:/core/images/chevron-down}}</$button>
</$list>
<$tiddler tiddler="$:/config/left-sidebar">
<$button actions="""<$action-listops $tags="+[toggle[$:/tags/Stylesheet]]"/>""" tooltip="Toggle sidebar left/right" class="tc-btn-invisible tc-hide-sidebar-btn">
<$list filter="[{!!title}tag[$:/tags/Stylesheet]]" emptyMessage={{$:/core/images/chevron-left}}>{{$:/core/images/chevron-right}}</$list>
</$button>
</$tiddler>
<!--
name : $:/core/ui/TopBar/menu
tags : $:/tags/TopRightBar
-->
Thank you so far
Stefan