UPDATE : Zahid Yener just posted an update on SCN to say that rather than clicking on the canvas you can just select a component and hit the tab key, which is much easier.
When I design a dashboard with Xcelsius / SAP BusinessObjects Dashboards, I find it impossible to fine tune the layout without using the cursor keys. As a result, I find it maddening when (seemingly at random) these cursor keys stop working for positioning Xcelsius components and almost as maddening when they (again seemingly at random) start working again.
It turns out that this is all to do with focus and the canvas. If you Alt-Tab (or use some other method) to switch windows and take focus away from Xcelsius, when you return you are left in a state where the canvas no longer has focus (at least in terms of being able to process cursor key presses). If you click on a component then the canvas still does not have the right focus, so when you press a cursor key, the component doesn’t move.
To resolve this, you need to click on the canvas itself (note: if you have a backdrop image or another component covering the whole canvas then you will have to move it as you need to click on the canvas itself). Once you have clicked on the canvas, you can then happily select any of the components and move it with the cursor keys … until, of course, you switch away from Xcelsius again, when you will need to go through this procedure again!