LuxCal 5.3.5 - Event window not centered

In LuxCal version 5.3.5, when opening the Add/Edit Event window, it is opened left-aligned on the screen, instead of horizontally centered.
This is a bug which can be solved as follows:
Edit the file "/common/toolbox.js" and perform a global replace of "screen.left" by "window.screenLeft" (3 x). Note the capital L in screenLeft!
This will solve the problem.