Readonly fields are not displayed the same

[marcus-oscarsson]

Read only fields are not displayed the same (greyed out/disabled). In the screen shot below, sub_sampling and frequencey are both readonly however only sub_sampling is the only one being displayed as "disabled". It seems to be related to the "description" display

[mockoocy]

I've tested this behaviour and it seems that when ui:readonly is passed into the uiSchema, RJSF sets the readonly HTML property for the text inputs, but disabled property dropdowns.
The CSS defined by Bootstrap includes styling for .form-control:disabled, but not .form-control:read-only - hence the background is only set when for the dropdown.

It could be resolved by either adding styles for .form-control:read-only or setting ui:disabled in the uiSchema instead of ui:readonly.