modal: Grey out the submit button when disabled.
modal: Grey out the submit button when disabled.

eeshangarg/zulip,rht/zulip,eeshangarg/zulip,rht/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip,rht/zulip,eeshangarg/zulip,zulip/zulip,andersk/zulip,eeshangarg/zulip,kou/zulip,kou/zulip,zulip/zulip,rht/zulip,eeshangarg/zulip,zulip/zulip,eeshangarg/zulip,rht/zulip,kou/zulip,andersk/zulip,andersk/zulip,andersk/zulip,zulip/zulip,zulip/zulip,kou/zulip,kou/zulip,rht/zulip,zulip/zulip,rht/zulip,zulip/zulip,kou/zulip,andersk/zulip,andersk/zulip