Currently FTL files are cached for 5 seconds when they are requested. In developer mode this should be removed to improve developer experience of the responsiveness of Magnolia to their changes. This will also enable using a "hot browser reload" mechanism like BrowserSync or LiveReload.
Change an ftl file. Refresh the webpage and see the change instantly.
Change the ftl file again. Refresh the webpage before 5 seconds elapsed and you will not see the change. Only after 5 seconds have elapsed since the last change was rendered will the new change be rendered.
freemarker.cache.TemplateCache sets the default refresh delay to 5s
The 'FTL lock' problem is solvable by doing this at L123 in FreemarkerHelper:
As this change will negatively impact performance, it should only be appllied when developer mode is enabled.
Please document also in a section about all the changes that developer mode activates.