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The sidebar is the pane on the left that contains the mini calendar, the event filter and possibly the event calendars.
Customizing the sidebar
Selecting "Custom" within the Features tab for Sidebar will result in an additional tab called "Sidebar." Here, you can configure the sidebar to your liking.
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Show sidebar
This is an attribute that will be updated by the widget when the sidebar is closed or opened by the widget's built-in buttons. You can change the value of this attribute in Mendix to open and close the sidebar programmatically too.
Show datepicker
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This setting will allow you to show or hide the date picker dynamically.
Show datepicker events
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Enabling this option will show little dots on the days there are events.