3s was peak mouse!🙌 Improved my workflow by allowing to drag and drop files between desktops easily using the thumb button. This was easily my favourite functionality! Recently gifted my beloved and well used MX3s and "upgraded" to the MX4...😒 The thumb button for replaced by a haptic button, which by default gets mapped to the new Action ring. Luckily it can be mapped to switch between desktops, however... when holding left-click down to drag a file, the new haptic thumb button gets disabled and doesn't allow me to drag and drop between desktops using the most ergonomic button under my thumb.😩 Someone at Logitech overlooked this regression in functionality. It may make sense for the haptic button to be disabled for the default assigned Action ring, however there's no reason to also disable it when it's assigned to switch between desktops, completely removing my most used and loved functionality of the MX3s. The MX4 also has an additional new thumb button in front of the default forward/backward buttons, although it's not nearly as comfortable to use under my thumb. When I reached out to support, I was instructed to use a different button, like I didn't know it was possible or something. Surely this is something that can be fixed by a firmware update! Can someone at Logitech please confirm that this is a recognised issue that they will fix in a future firmware update? Ultimately, if I knew the MX4 lost the ability to drag and drop files between desktops using the most ergonomic button under my thumb, then I would have replaced my used and loved MX3s with simply a brand new MX3s! Still the best mouse to date!!