Annotation tools can be selected by the keyboard shortcuts [1, 2, 3, ...]. However double pressing any of those keys doesn't freeze the annotation. Also double tapping an annotation tool through the touchscreen doesn't freeze it. SOFTWARE VERSIONS (available in About System) KDE Plasma Version: 5.14 KDE Frameworks 5.50.0 Qt 5.11.1 (built against 5.11.1)