ExtJs has row and cell editing plugins. Unfortunately they do not allow the cells in bulk/batch mode. I have tried to implement bulk edit using custom selection replicator. and popup form for single and multiple columns edit.
This post is about an editable grid with editable multi-select combobox. This solution is for extjs 4.2. In the newer versions (>= v5.1) the ‘multiSelect’ property is deprecated. If you do not want to have problems during your framework upgrade in the future, I would suggest not to use the deprecated functionality and use the tag field.