Hello!
Unfortunately I haven’t found any information about column collapse event or making some columns constant seeing. I mean is there any way to permit collapsing columns except for the specified. And second: how could you catch column collapse event if it possible?
There is no specific event for this, but you might be able to achieve this by overriding the method Table.setColumnCollapsed(). This is currently also called (in a loop) when the client side informs the server of which columns are collapsed and which are not.
I am not certain of whether the client informs the server immediately about collapsed columns, or if another UI action is needed to trigger this.