It's doubtful that dark themes have any impact on battery life. To my knowledge unless you have an OLED display on your laptop, the light is generated by a flat panel with a uniform brightness. That is there is no local dimming. So in order to make any whites actually "white" the backlight needs to be a full brightness.
That said, if you have a dark theme everywhere you might want to turn down the entire screen brightness at the system level. That definitely will impact your battery life.
The IDE already comes with several dark schemes build in. Further
schemes should use the above way.
If someone wants to supply a package that allows to distribute schemes
(and maybe other stuff) in an OPM like fashion, then that can be
> If you want to install the theme manually to test for yourself it
> requires a couple of steps.
> 1) Go to tools, options, display, colors
> 2) Hit the save button and create a new theme named dark.xml
> 3) Exit lazarus
> 3) Open you lazarus config userschemes folder
> 4) Overwrite dark.xml with this file
> https://cache.getlazarus.org/themes/dark.xml > 5) Restart lazarus, go to tools, options, display, colors, and choose
> darker from the drop down