1

Actually plasma moves plasmoids, when screen resolution is shrinking. My motivation is to solve matters with running application like games, which change screen resolution to too small or don't restore it correctly(for example segfault). I will propose two solution:
1, Add dbus API to KWin and Plasma. KWin will change resolution for systemsettings(it will use KWin dbus API). KWin API will also call Plasma API to move plasmoids.
2. Add new X.org call to change resolution from systemsettings and change behavior of current API to wait for application exits to restore previous resolution

First solution won't be useful to solve matter with misbehaving apps.