About 2.8 UV editing work space, there seems no “tool icons” in left side tool section of 3d view edutir and UV /image editer windows. (clear seam, mark seam, and UV unrwap options)
Though I found those commands in header (or bottom) menu of 3d view or i can use short cut. but I believe, work space is desigend to find and use tools which correspond to current work type. Most of new user may serch those UV tools in tool sections.
We need, uv tool buttons, when we choose “edit mode” with “UV editing” layout.
I do not against we keep UV menus in header of 3d view editor, but I can not approve
remove button to set seam , or unwrap button from 3d view.
Please compare 2.79UI
we only need one-click those tool button, to set seam and unwrap after we select " shading tab." in tool shelf. though there is no uv command in header.
About current 2.8 UI, with UV edit layout, we need to go header>UV>mark or clear seam.
it need at least 2 step. for each uv command.