Designer should not reload after each process save, because all opened palettes are closed. You have to click several times to open them again and this behavior can be improved to become more user friendly. Reloading of the Designer is caused by Guvnor, but Tihomir suggested that this could be solved simply by adding additional information about opened tabs to the cookies file. It's just a feature request, but not so difficult to solve, so I think it can be included in brms-5.3.1.
Tihomir Surdilovic <tsurdilo> made a comment on jira JBPM-3778 Please file this issue as a Guvnor issue. Guvnor reloads the asset window on save-operations. For designer-specific issue please file a new one for remembering the pallete state. Thanks.
Tihomir Surdilovic <tsurdilo> updated the status of jira JBPM-3778 to Resolved
Tihomir Surdilovic <tsurdilo> made a comment on jira JBPM-3778 see comment above
Closing the bug, since this bug won't be fixed in brms-5.3.1. Also it is not an issue of the process Designer, but it has to be fixed in Guvnor. See the new Guvnor related Bugzilla https://bugzilla.redhat.com/show_bug.cgi?id=856063.