When comparer is set and returns true, the property will still not be updated if the value equals to the old one

[LastLeaf]

When comparer is set and returns true, the property value comparison is still executed:

glass-easel/glass-easel/src/data_proxy.ts

Line 492 in 4eb7538

if (!excluded && oldData !== filteredData) {

Is it expected?

[LastLeaf]

comparer should refers to "does this change require template updates?"

It should triggers after the data observer (if any), since data observers always trigger no matter data changed or not.

[LastLeaf]

Consider allow comparer in common data fields in future.