Here are some screenshots, some taken on a dark-on-light GTK theme, others on a light-on-dark theme.
An item's editor interface.
The history of the changes to a database.
The search interface.
The scheduler in an item's editor, used to set recurrence rules.
The interface that lets define a new recurrence rule for an item.
Another example of the recurrence rule editor.
The schedule view.
Multiple databases open; note how the menu bar, the logs and the schedule navigator have been hidden.
Unallocated time (gaps) and time intervals shared by multiple events (overlappings) can be highlighted in the schedule.
Alarms in the schedule are highlighted in amber by default.
The log for snoozed, dismissed or deleted alarms.
The alarms window, provided by the "wxalarms" plugin from the "outspline-extra" component.
The properties of a database.
The about window.
The dialog that appears when a database has not been opened for a long time and searching for past alarms takes longer than expected.
The dialog that appears when a database needs to be upgraded.