The theme has a color for each keyframe type. This is exposed in RNA and
the preferences UI as an RGB color, so without alpha channel. The code
that loads the color from the theme, however, does include that
unsettable alpha channel, though.
In practice this doesn't cause issues, as the versioning code ensures
that the default colors are stored with `alpha=uint8_t(255)`. While
developing, however, this caused me considerable headscratching, as I
was missing that little bit of versioning code, which means that the
default color was set to all-zeroes, and thus had a zero alpha.
This is now resolved by altering the drawing code to only load the RGB
component from the theme. This way only the user-settable bytes are
loaded, while the alpha component is handled a different way (setting it
to an absolute value, instead of multiplying the theme value).
No user-perceivable changes, just some developer comfort.
Pull Request: https://projects.blender.org/blender/blender/pulls/120311
bc764072f5