New items need to be appended to sourceParent index, not the index itself
New items need to be appended to sourceParent index, not the index itself

Part of review 109727

leonhandreke/ktp-common-internals,KDE/ktp-common-internals,KDE/ktp-common-internals,leonhandreke/ktp-common-internals,KDE/ktp-common-internals,leonhandreke/ktp-common-internals