- Do I have to open the folder I want to tidy up?
No, this is not necessary. All icons can be also rearranged if the
folder is closed. But of course you'll see the result only when you
open the folder.
- Do I need to select the Icon view in the finder?
No, the icons can be rearranged in all other views as well, but
tidy up the icons will only affect the icon view, so to see the
result you have to select the icon view.
- I click the tidy button, but nothing happens, though the "Icon view" is selected?
Probably you've selected the "Keep arranged by" option in the "view
options" of the Finder. This setting has the highest priority in
the finder, which means if this option is switched on, the finder
won't allow any other positioning. Switch this option off for all
the folders you want to clean up with "Tidy" and it will work.
When using the "FileVault" of the MacOS for your user directory you have a problem. Unfortunately the Finder refuses to realign icons which are located in the FileVault. This is a limitation of the Finder.
- "Tidy" aligns only some icons, certain files like applications won't be cleand up
This is a bug of the Finder of MacOSX. The Finder just refuses to
move certain file types to a now position. If "Tidy" tells the
Finder to move such an icon to a new location, the Finder just
answers that the object can not be found, even if it is there.
A small but strange experiment:
Open a window in the Finder and create a folder named "xxx" there. Now tidy up this window with "Tidy". You'll see that the folder "xxx" will be correctly aligned according to the Tidy settings. Now rename the folder from "xxx" to "xxx.app". The Finder now changes the icon of the folder and "Tidy" is now unable to align this folder. The Finder just refuses to realign files or folders with the file extension ".app".