Dark Mode is a feature that allows Mac users to switch to a completely
different darker interface that adjusts everything on the screen, system-wide.
A partial implemention of this mode appeared in version 10.13 (High
Sierra) of OS X but the complete feature was introduced in version
10.14 (Mojave).
Prior to Mojave, you could only turn on
Night Shift and you could use a dark menu bar and dock.
Dark mode can be activated and deactivated at the system's level from the
General System Preferences panel.
Alpha fully supports Dark Mode and offers a few additional features.
When Dark mode is activated, all window frames, icons, dialog boxes
and menus in Alpha are redrawn darker. The only exception is the background
of the text area in document windows: since Alpha provides syntax
hilighting, the syntax colors may render poorly if the background is too
dark. So, by default, the background color is left as is (white by
default). But some may find it easier on the eye to also have a darker
background: there is a preference called Allow Dark Mode Text to
control this behavior. It is located in Alpha's Appearance Preferences panel. If this preference is enabled, the text area of document windows will
have a darker background color when Dark Mode is activated.
In that case, by default, the background of the text area is painted in
light 80% gray. The color used can be changed with the Dark Background
Color preference also found in the Appearance Preferences panel.
The following two images show the difference:
Note for developers
AlphaTcl package writers can query the current theme in their scripts using the following
command:
getAppInfo darkMode
It returns 1 if the dark mode is active, 0 otherwise.
There is also a themeChangedHook with which you can register a proc to invoke when the
user changes the mode in the System Preferences.
