On
Handles taps on the main toolbar's navigation (up / back) icon.
This is the Compose-toolbar replacement for Toolbar.setNavigationOnClickListener on the removed View main toolbar: set the icon with com.pspdfkit.ui.PdfUi.setToolbarNavigationIcon and this listener with com.pspdfkit.ui.PdfUi.setOnToolbarNavigationClickListener. The SDK has no default navigation behavior, so the tap does nothing until a listener is set.