The general idea is to support user-units inheritance. The
UNIT_BINDER allows wrapped controls to inherit units from their
parent dialog, while KEYWAY_HOLDER and DIALOG_SHIM allow child
KEYWAY_HOLDERs or DIALOG_SHIMs to inherit units from their
parent.
The GetUserUnits() method signature has to move to KEYWAY_HOLDER
rather than KEYWAY_PLAYER (where it makes more sense) as it’s the
only common ancestor of KEYWAY_PLAYER and DIALOG_SHIM.
As long as we'll be using the UNIT_BINDER more widely, it also
makes sense to move evaluation and validation into it.
This commit also provides eeschema’s DIALOG_LABEL_EDITOR and
pcbnew’s DIALOG_TRACK_VIA_PROPERTIES and DIALOG_SET_GRID as
models of how to use the new user-units inheritance, eval, and
validation.
Fixes: lp:593795
* https://bugs.launchpad.net/kicad/+bug/593795
(cherry picked from commit c8bc53e)
74acb76e7f