Spacer/divider widget

Currently it is very cumbersome to adjust visual spacing when building workspaces. It would be nice to have a dedicated widget, that can be used to add different visual dividers or just whitespace between widgets.

When adding this widget, you can choose how tall it is. Then you can choose the divider graphics (default being empty), which would then offer nice collection of different looking vector elements (like lines and shapes). Colors of these elements would come from widget style highlight color.