Just an experiment. Not sure if there is anything here we might want to use...
I've always felt that the large "Thumbnails" view in the File Manager was a bit wonky. The difference in sizes between the file and folders versus the previews make it an awkward read. The vertical alignment is clumsy with the names of folders and most documents being far away from the icon. And so much wasted space in vertical rows that are unnecessarily large.
The following image shows the changes in this patch. The top showing how it looks now, the bottom after the patch is applied (and with one image file replaced in the source):
The preview icons (folders and files) are increased from 48 to 96 pixels. The resulting image in the source is still only 384x384 since there are so few images on the sheet. But it does give more detail and allows for better scaling without jaggedness. Here I am also making the folders have a tighter bottom bend and are made to look a bit thinner. And color is added for better visual separation between folder and files since they aren't really siblings, but more like branches versus leaves of a tree.
The document icon is given a slightly smaller corner bend proportionally, the top-left gap closed, and a background added to give it some weight. The idea is to make it look less like something disabled.
Thumbnail images (blender files, images, videos, and fonts) are made rectangular landscape (Max 128x96), rather than square. It is the same amount of space for the file name but it quite drastically decreases the row spacing so you get more information on the page. The sizes and spacing makes for much more consistent rows and the names are never far from the associated icon.
Dropshadows are added to movie thumbnails to match those of image thumbnails. The small "document type" icon is placed in the center of the larger document icon, rather than off to the side. Font preview images no longer show the "F" on top of the font preview text. Font preview text reduced to three lines to better fit the preview size.
The captures above don't really do it justice; best to compile the patch and give it a spin yourself. To do so also requires that you replace "..blender/release/datafiles/prvicons.png" with the following image: