During startup, TiddlyWiki executes any ActionWidgets found in tiddlers with the following system tags:
Startup actions are useful for customising TiddlyWiki according to environmental factors such as the screen size. For example, the following action widgets when placed in a tiddler tagged will cause the sidebar to be hidden by default when the screen width is less than 1000 pixels:
<$reveal type="lt" state="$:/info/browser/screen/width" text="3000">
<$action-setfield $tiddler="$:/state/sidebar" $value="no"/>
</$reveal>
<$reveal type="gteq" state="$:/info/browser/screen/width" text="3000">
<$action-setfield $tiddler="$:/state/sidebar" $value="yes"/>
</$reveal>Note that global macros are not available within startup action tiddlers by default. If you need to access them then you'll need to explicitly include them with an import pragma at the top of the tiddler:
\import [[$:/core/ui/PageMacros]] [all[shadows+tiddlers]tag[$:/tags/Macro]!has[draft.of]]