Ok, I try to explain what is going on here.
There are two ways of solving the dots issue. But before you decide for a variant, you have to make a preliminary consideration: There is always a space available between the last character in the line and the page number. Because lines can have different length or an m-character has a differenzt width than an i-character > those spaces are always different!
1. Fill the space (the tab) with an underline:
If you insert e.g. a thin space after your last character, then a right indent tab and then a en-space before your number and give a underline to your right indent tab, the first dot will start immediately after the thin space and will end exactly before the en-space (note that in practice there is a bit of room because of the tracking of the character). If you insert those dotted underlines for multiple entries and draw a guide on one of those points, you will see that the dotts are not vertical aligned to each other. This happens, cause the distance of two horizontal dotts is calculated by the available space.
2. Fill the space (the tab) with a leader:
Because it is important that those dotts are vertically aligned, the start and end point is not realy defined by the end of the thin space or the beginning of the en-space. It may happen, that you insert a thin space and the dot will start visualy at an en-space. In the end you will get different spaces at the beginning and at the end, but perfectly aligned dotts.
I like to compare this with justified or left-aligned text: Justified > all lines have the same left and right edge. To achieve this, the space between words must be different. Left aligned: same left edge, but different right edge. The width of all spaces between words is the same.
Now clear?
Kai
P.S.: If the spaces are to big, remove the thin space and the en-space and see what is happen.
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