rctlmk

Rewrite `sys` module declaration

2

I replaced the `cfg` attributes with the `cfg_attr`. It doesn't really change anything, just looks a little more neatly.

Fix stacked BarChart offsets

1

* Closes #4454

**Describe the bug** I was working on a little app with a stacked bar chart, and came across this possible bug (black lines were added in Paint for illustrative purposes):...