This dialog allows you to control the way tabs are ordered and reordered when windows are opened, closed and switched.
MDI ordering
With this option selected, the tab order corresponds to the MDI window order. This means that the most recently used window gets the left-most tab, followed by the next-to-last used window. The least recently used window has the right most tab.
Since the MDI window order changes with each window operation, so will the tab ordering.
Alphabetical
With this option selected, the tabs retain alphabetical order at all times.
Preserve tab ordering
With this option selected, the tabs keep their order even when windows are closed, opened or switched. The first window you open gets the left-most tab, with successive windows/tabs to the right.
Reorder Now (button)
Reorders the tabs with the most-recently-used tabs (windows) first.
Preserve tab numbering
When this feature is disabled, and a tab in the 1..9 range is closed, the remaining tabs are renumbered (e.g., closing tab 2 will cause tab 3 to become tab 2, tab 4 to become tab 3 and so on). With this feature enabled, closing tab number 2 will leave tabs 3 and above as-is, and there will be no tab number two. WndTabs lets you access tabs 1..9 using keyboard shortcuts, so you would probably want opened windows to keep their corresponding tab numbers throughout the session.
"Preserve tab numbering" is not available with MDI tab ordering.Renumber Now (button)
Redistributes tab numbers so that the left-most tab gets the number "1", the second from the left gets the number "2", and so on. This command is useful if you've closed windows in the 1..9 range, and want to reclaim the number of the closed window.
Note that files on grouped tabs will not necessarily get sequential numbers.Attempt to fill indexes 1..9 first
When "Preserve tab numbering" is selected, controls whether or not new windows should get tab numbers in the 1..9 range first. Assuming you have tabs with the numbers 1..5 and 7..9, opening a new window with this option on will give the window a tab with the number 6. Otherwise, the tab will be appended as the last tab and will have no number.
Save tab numbers when closing the project file
With this option enabled, tabs keep their numbers even after you close your project file. This is a handy feature if you are used to the tabs (and their keyboard shortcuts) being in a certain order.
The positions are saved in your project directory in a file called "<project-name>.positions".