When I choose to view the Folder tree in dolphin, the icons shown match the ones indicated in .directory.
That does not happen in Konqueror (except for some strange exceptions): the tree folder usually show just the default folder icon.
Is there an explanation for this or, better still, a solution?

What exactly do you mean with "view the Folder tree"? Does it mean

a) Open a folder in Details View and expand the subfolders, such that a tree structure is shown, or
b) Look at the Folders Panel in Dolphin or the sidebar in Konqueror, respectively?

My system is in Spanish, so excuse my imprecision.

What I mean is that in the konqueror side bar, when the option that I have selected the folder tree (either starting in / or ~), the icons shown are not the ones specified in the .directory file of each directory.



(What I discovered yesterday is that this happens when I unfold a tree by clicking in the arrow to the left of the folder. If I instead select the folder by clicking on the folder icon, it unfolds correctly, i.e., showing the desired icons. I do not, however, want to do this all the time, so it is not a solution.)

You're right, I can confirm this behaviour in KDE 4.8.3. Looks like a Konqueror bug.