This fix works for me since 4.0.1
Code:
Ext.override(Ext.grid.Lockable, {
reconfigureLockable: function(store, columns) {
var me = this,
lockedGrid = me.lockedGrid,
normalGrid = me.normalGrid;
if (columns) {
Ext.suspendLayouts();
columns = me.processColumns(columns);
lockedGrid.setWidth(columns.lockedWidth);
lockedGrid.reconfigure(store, columns.locked.items);
normalGrid.reconfigure(store, columns.normal.items);
Ext.resumeLayouts(true);
}
if (store) {
store = Ext.data.StoreManager.lookup(store);
me.store = store;
lockedGrid.bindStore(store);
normalGrid.bindStore(store);
} else {
lockedGrid.getView().refresh();
normalGrid.getView().refresh();
}
}
});