D13450: Add arrow keys to move and resize selection rectangle

[Yuri Chornoivan]

yurchor accepted this revision.

REPOSITORY
  R166 Spectacle

REVISION DETAIL
  https://phabricator.kde.org/D13450

To: sharvey, rkflx, ngraham, #spectacle, yurchor
Cc: kde-doc-english, abalaji, #spectacle, skadinna