ctrl+mouseDown event

[anneg]

Have you tried this?

onLeftMouseUp event only when Ctrl is held?

You can add a callback for ctrl-left mouse up event with: var handler = new Cesium.ScreenSpaceEventHandler(scene.canvas); handler.setInputAction( function (event) { var mousePosition = event.position; // … }, Cesium.ScreenSpaceEventType.LEFT_UP, Cesium.KeyboardEventModifier.CTRL); Dan