For me, the following is the most infuriating aspect of using the Notes email client. Notes has a preview pane like most other modern email clients. You can even position it vertically, which I quite like, because I can see more of the message in the preview pane as well as more messages in the message list, but I digress.

I use the scroll wheel on my mouse to scroll the preview pane, but here comes the infuriating bit: Notes insists that you select the preview pane by clicking on it before the scroll wheel works. In fact, it seems that any panel in Notes that has as scroll bar must have keyboard focus before you can scroll the panel with the scroll wheel.

Applications that support the scroll wheel correctly should scroll any pane under the mouse cursor regardless of whether or not that pane has the focus. This kind of click-to-scroll behaviour was common when scroll wheel mice were new and not widely supported, but the scroll wheel mouse has been around for 13 years now!

Another issue that compounds this problem is that keyboard shortcuts don't work when the preview pane is selected. So, this means a two-handed operation (using my left hand to move from message to message using the up/down arrow keys, and using my right hand to scroll with the mouse) to quickly flip through a series of emails is impossible.

Fortunately, there is a solution: KatMouse fixes Notes (and other scroll-wheel-unfriendly programs) so that the scroll wheel works on whatever pane is currently under the mouse pointer. It even scrolls panes when other applications have the focus. It's brilliant ... sanity has been restored!