Open new detail dialogs only if pressing shift/ctrl

Otherwise the last dialog will be used.
Move selected element left/right via cursor keys
Don't focus detail dialogs on creation
Add marker for current element

TODO:
- remove marker when dialog is closed
- change style for inactive dialogs?
Make ElementMarker a separate component and handle Close event
Merge branch 'thin-select'

Enable reselecting a different element in the same dialog when not
holding shift/control. This also works with Left/Right cursor buttons.
For each element detail dialog a marker is shown in the graph.
Use scale invariant patches for Element markers

This fixes various problems:

- when y data range is too small the patches were invisible (zero
  height)
- element patch heights were not updated when rescaling
Get ymin,ymax from config file for element selection markers
Merge branch 'scale-invariant-patches'