> When I delete a single thumbnail, the active window stays as thumb-view but when I delete multiple files by selecting multiple thumbnails, the active window is deselected.
I can't reproduce this here.. When I keyboard-select (shift-arrow) multiple files and press DEL, I get a confirmation dialog, I press 'A' for 'Yes to All', the files are deleted and my cursor is back in the thumbnail listing where I can select and delete some more.
In Options | Preferences | Confirmations, I do have the confirmation for 'Deleting files' on. However, down below in that dialog it shows that I have disabled 3 warning messages, and if memory serves one of those was the irritating "Are you really, really, REALLY SURE that you want to delete these files??"-message. Could it be that you have that one still active, and that that's what is stealing focus away from the thumbnail listing?
In Options | Preferences | General, I have 'Use Windows recycle bin settings' On.
In Options | Preferences | Thumbnail View, I have 'Watch changes in folders' Off (due to some very large folders that would slow things down too much). 'Enable color management' is off too.
I can't seem to think of any other settings that may affect the deletion of files and the redrawing of the thumbnail listing.