) drop down menu, you can select the Icon Arrangement to use for either Memorizing or Restoring Icon Positions (see above). Depending on how many Icon Arrangements, the action drop down menu can look something like
After the first time use
Depending on whether you checked “Automatically Restore Icon Positions at start” and/or selected “Quit”, DIM will behave differently when you run it.
1) To Always Get Back to main DIM window
If “Automatically Restore Icon Positions at start” is checked and “Quit” is selected, you will not be able to get back to the DIM screen to change icon arrangements. By holding the command (⌘) when starting, you will get the window to appear (starting this way will not restore the icon positions but will simply present the window). This allows you to reconfigure DIM. If you are having problems doing this, the best way is to find DIM, select it and then hold command (⌘) and press the letter “o” (for Open), let go of “o” but keep command (⌘) pressed until DIM starts.
2) If both Automatic Restore and Quit are selected
Then DIM will simply restore the icon positions using the selected Icon Arrangement (as specified in the “Use Icon Arrangement” line) without asking and quits automatically (wonderful if DIM is specified as a Login Item, but if you're running Ventura (macOS 13) or later, DIM Helper is a better option: see 14 below').
3) Restoring icon positions
By pressing the “Restore Icon Positions” button, all icon positions (if they still exist!) will be restored according to the selected Icon Arrangement (as specified in the “Use Icon Arrangement” line). If the screen resolution has changed since the last “Memorize Icon Positions” or the original running of DIM, the Desktop icon positions are relatively scaled in the new screen resolution. If there are new icons on the Desktop, they are left where they are. This procedure may take a few seconds, but it’s not like you can’t do something else as it finishes its task.
4) (Re)Memorizing icon Positions
By pressing the “Memorize Icon Positions” button, all the icon names and positions will be updated in the preferences file for the currently selected Icon Arrangement (as specified in the “Use Icon Arrangement” line). Any missing icons are included in the Icon Arrangement (see below).
5) Forgetting Missing Icons
By holding the option key (⌥) the "Memorize Icon Positions" button turns into "Purge Icon Positions". Pressing this button, any missing icons will be excluded in the Icon Arrangement. Otherwise it is identical to having pressed "Memorize Icon Positions".
6) Automatically Memorizing Icon Positions
By selecting "Memorize Icon Positions" check box, DIM can automatically memorize the current Icon Arrangement either "at Quit" or at selected time intervals. For this to work, DIM needs to stay running, of course. The current Icon Arrangement will be overwritten when this action is triggered.
7) Selecting an Icon Arrangement (see "Quick Restore and Memorize" below)
By pressing the action (
) drop down menu, you can select the Icon Arrangement to use for either Memorizing or Restoring Icon Positions (see above). Depending on how many Icon Arrangements, the action drop down menu can look something like

Once you select an Icon Arrangement, the “Use Icon Arrangement:” and “Number of memorized Desktop Icons:” will be immediately updated.
8) Renaming, reordering, deleting and adding Icon Arrangements
By choosing the “Edit…” option in the action (
) drop down menu, you will be presented with a dialog something like:

Here you can see all the saved Icon Arrangements (four above). You can then reorder the saved arrangements (drag and drop in the list), change the Icon Arrangement names (double click), add a new arrangement (press the “+” button) or delete the selected arrangement (press the “-“ button). Pressing the Done button will take you back to the main window.
Pressing the “+” button allows you to create a a new Icon Arrangement. After pressing “+” you will see something like:

The first pop-up menu ("Container to memorize") allows you to select either the Desktop or any Finder window that currently is in "icon view":

If you select a Finder window, then you can also memorize the position and/or size of that Finder window. The position will be scaled if the screen size/resolution changed. The size will be unscaled.
Regardless, you can then input a name for the Icon Arrangement. Pressing “Add” will cause the current icon positions to be saved under this new Icon Arrangement.
9) Which icons are not saved in an Arrangement
By choosing the “Select unmemorized Icons” option in the action (
) drop down menu, any icons on the Desktop/Finder window that are not in the current Icon Arrangement will be selected on the Desktop/Finder window. If no such icons exist, you will be rewarded with a beep.
10) Hiding/unhiding Desktop icons
By choosing the “Hide Desktop Icons” option in the action (
) drop down menu, any icons on the Desktop will be hidden. By selecting "Show Desktop Icons", they will be unhidden.
On macOS 13 (Ventura) and later, the app Hide Icons is bundled inside of DIM as a LoginItem instead. By choosing "Start Hide Icons", Hide Icons will be run immediately and at login. You can stop it either through DIM or directly through Hide Icons menu.
11) Checking for updates
By selecting "Check for update..." in the main DIM menu, you are granting permission for DIM to reach out (via https) to an update server. If there is no update available or an error occurs, then this menu item will be updated accordingly. Otherwise a sheet will appear on the main DIM window giving an option of downloading the update, visiting the website or canceling. If downloading is chosen, the update will be downloaded to the local Downloads folder and the menu item will change to "Locate new update". You should then quit DIM and replace it with the updated version. Otherwise, if there is an error, the menu item will be updated.
12) Starting from the command line (Terminal or script)
One can start DIM from the Terminal command line by typing open -a DIM (or open -b com.parker9.DIM-4). One can also pass command line arguments via open -a DIM --args [...] option. The list of valid command line arguments are:
where [arrangement] is an optional name of the Icon Arrangement to use. If not provided, the current Arrangement is assumed. Multiple options can be invoked and they will execute from left to right. Therefore, if "--quit" is present, it should be the last option on the command line. For example, open -a DIM --args --add "Start Up" --restore --select-missing-icons would memorize the current Desktop icon arrangement in "Start Up" arrangement (creating one if necessary). Then DIM restores the icons according to the current arrangement. And finally DIM would select any icons that are not present in the current arrangement. DIM will stay open, since the --quit option was not used.
13) Quick Restore and Memorize
By right-clicking (or holding) the Dock icon, a menu for Restore or Memorize each of the stored Arrangement allows for quick Restore/Memorize. "Restore" and "Memorize" options use the current Arrangement. Holding the option key (⌥) while invoking the Dock menu changes "Memorize" to "Purge". If DIM is not running, then Dock will only give a few options, but if selected it will start DIM, do the requested action and then quit DIM automatically for you.
14) DIM Helper and actions after certain events
On macOS 13 (Ventura) and above, choosing “Start DIM Helper” in the action (
) drop down menu, you can specify actions DIM should take when certain system events occur. When DIM Helper is first started (or, in the action menu, select "Edit actions..." under the "DIM helper is running"), the following will be presented:
Clicking on any one Event on the left, you can Enable and specify actions that DIM should do when the event happens. You can also specify a delay between the event and executing the action(s). These actions will only occur if DIM is not running. If DIM is running when an event happens, the action(s) will not execute. Details of allowable actions are described above in 12. By default, we enable the first three Events. DIM Helper must remain running, but you can quit DIM.
G.J. Parker - http://www.parker9.com (Entonos)