Please describe the problem:
When bitmap image is set as a custom icon for a folder, tiny (48px high)
borderless thumbnail is generated instead of nice thumbnail with frame and
dropshadow.

Please note this is not just an aesthetic glitch - it seems to have some
performance issues, too, as folder with many custom icons for folders now loads very slowly and with high CPU load.

This bug is still present in 2.26.2. Last time folders with a custom icon were
thumbnailed correctly was 2.20! (If I remember correctly, this behavior was broken in 2.16, then fixed for 2.18 and worked in 2.20, too.)

See also similar bug 524392 filed against 2.22, there is a nice example attached there:

http://bugzilla.gnome.org/attachment.cgi?id=108029

AFAIK this problem has been also reported here:

http://ubuntuforums.org/showthread.php?p=6949438
https://bugs.launchpad.net/nautilus/+bug/206487

Steps to reproduce:
1. create a new folder, select "Properties", click on icon and navigate to some JPEG image, click it to select it as custom icon for this folder
2. compare thumbnail displayed for folder and thumbnail for JPEG image which was used for custom icon

Actual results:
Folder custom icon has small size and missing frame and dropshadow as compared to original image; reloading folder with many (e.g. 20+) folders with custom icons is very slow compared to reloading folder with e.g. JPEG files only

Expected results:
Folder with custom icon should be thumbnailed the same way as image which was used for custom icon, including normal size, frame and dropshadow.

Does this happen every time?
Yes.

Other information: