I have an idea for a tree grid with full paging/virtual scroll support even in lower levels.

I will try to explain my thoughts, maybe you can implement it in one of the next versions of TreeGrid.

I will explain using a concreate example.

Imaging you have only one root folder.
In the second level you have 980 of folders.
The pagesize for paging is 100.

When you expand the root folder, the first page (1 – 100 of 980 rows) is loaded from the server, and for each folder/row a <tr> is created.
For each remaining page (rows 101-200, 201-300, … 900-980) one placeholder-row is also added to the grid. (The hight of this placeholder-row is rowheight * pagesize; so for my example it would be 34px * 100 rows = 3400 px for page 2-8 and 34px * 80 rows = 2720 px for page 9.) For the placeholder row you add an inview-eventhandler.
As soon as the user scrolls down and one of the placeholder-rows comes into view, jqgrid loads the corresponding page from the server and adds all the rows for that page to the grid. After adding the loaded rows – the placeholder row is removed from the grid.

Please tell me what you think about this solution.