@Patch I was thinking about your scrolling issue whilst I was writing my example Tabs down. Actually on reflection, while I am focused on the length of the Tabs, your point is very valid from a website best practice point of view.
When you are visiting a website you always want the menu options to be at the top or LHS and to be static while you scroll down the page. Manager does not adhere to this best practice as you have to scroll up to select a tab if you have scrolled down in payments or Journal Entries etc.
I believe that creating groups similar to what I have suggested and moving all of this up into a fixed header at the top will be far better as this will negate the need to scroll back up, make more effective use of the wasted space on top and also give more width to forms so you never had to scroll left or right. The tabs minimise is a nice feature but is actually fixing a symptom of a problem.
So my suggestion would two other separate issues as well as my own. Scrolling up to access tabs and left right scrolling within forms eliminating the need for a tabs mimise.