Filemaker will not update code for items listed. They may continue to work, or may not. Filemaker will not offer tech support for items that are not actively being coded in newer releases. "That is depreciated, we recommend using something else."
Thank you for explanations !
In facts, i am perplexed by this huge list of layout themes becoming unsupported.
I am even perplexed by the fact itself, that a layout theme can become unsupported (just three years after the theme feature became available).
Will post these comments and other related questions to Feedback product section.