Rulers in <richtext>
Legend (n and m here are some decimal digits):
“healthy” columns:
| caption | meaning |
|---|---|
| nn | fixed column, width of the column in pixels |
| nn% | percentable column, width of the column in percents |
| <nn> | auto column, nn here actual width in pixels |
| >nn< | auto column reached its' minimum |
“problem” columns:
| caption | meaning |
|---|---|
| nn(mm) | fixed column, declared as nnwidth but resized to mm pixels. |
| nn% | percentable column but not enough space to render it using nn% value. |
