Start with looking through the list of Questions and answers below, to see if your question has already been answered.

Note: when reporting bugs please try to include the steps needed to trigger it. This helps greatly in locating the source of the bug, so that it can be fixed in a timely manner.


You are also encouraged to use this email address to request new features or inquirer about other product related issues.

Questions and answers

Using image folders

Fresco will show all the images in a folder (and its sub folders) when added as an image source. Add individual sub folders instead if you want to limit which images that appear in the preview area. This may require moving some images into new sub folders or reorganizing some folders, so that you only get the images that you desire.

Fresco has a max limit on the number of images shown in the preview area, this is done for performance reasons, but it's also a good indicator that you should probably de-select some of the image sources (that are selected) as your going to have way to many images to look through.

If you do run into this limit (1000 images) with a single image source (folder), you will have to split the folder into two (or more folders) to be able to view and use, all of the images.

What are the effects of changing display settings?

The resolution and arrangement of displays can be changed in System Preferences → Displays. Displays can also be added and removed by plugging them in and by unplugging them. This results in the behaviors listed below (tested using 10.7).

Display arrangement change

The displays will continue to show the same image content even if their relative position is rearranged.

Display resolution change

The image will be resized to fit, this can result in a slightly fuzzy image if the new size is larger. The image will be clipped if the aspect ratio changes.

Remove a display

The remaining displays will continue to show their assigned desktop picture.

On macOS 10.9 (or later) this also means that all but the leftmost desktops from the removed display, will be transferred to the remaining display(s). The desktop picture of a transferred desktop may be scaled and clipped if the displays differ in size or aspect ratio.

Add a display

The added display will either show the image it was previously set to or a default image if the display hasn't been used before. A default image may also be shown if the previously used image has been deleted.

MacOS 10.9 (or later): plugging in a previously used display, will also result in any desktops previously transferred off from it, to be moved back.

Note: setting desktop pictures using System Preferences → Desktop & Screen Saver → Desktop and using the Fill Screen option will result in the same behavior.

How to uninstall

Uninstalling consist of two actions, removing the app and optionally removing its data.

Migrating app data to another Mac

If your migrating data manually to another mac, you may consider moving the old Fresco saves from the old mac, to the new one. Note that this is only meaningful if there are saves that match the display resolution and arrangement used on the new mac. To do this:

Managing Saves

It's currently only possible to create and delete saves for the current display arrangement. To show other saves you will have to connect/disconnect displays, switch resolution and arrange displays as required—to match the desired set of saves.

A trickier but more powerful solution is to use Finder, to remove or add saves manually. The steps are as follow:

Organization of saves:

Each fulldesktop w… h… folder contains saves (save … folders) for desktops of size w × h. Desktop size is defined as the smallest rectangle enclosing all displays. This usually matches one arrangement of displays but could match several.

fulldesktop w3360 h1050 could e.g. be two 1680 × 1050 displays side by side. But three 1120 × 1050 displays1 side by side or two 1680 × 900 displays1 side by side with one placed slightly higher than the other (resulting in a desktop height of 1050) would also form a 3360 × 1050 desktop.

1: assuming that such displays exist.

Each save … folder containing a preview image and a info.plist file—both store info shown in the save listing. There will also be one desktop-section-x…-y…-w…-h… file for each display used. The x and y values specify the position of the display relative to fulldesktop (where 0,0 = bottom left corner). w & h is the size of the display that a section image is intended for.

How to find the ~/Library folder

~/Library refers to the Library folder of the current user.

The users Library folder is hidden when using macOS 10.7 (or later). On 10.6 (and older) it will be visible as a folder named Library, in the users home folder.

The easiest way to access the Library folder on macOS (when using 10.7 or later) is to click the Go menu in Finder and hold down the Alt/Opt key to get Library as a menu option.

Optimized Storage, iCloud Drive and other sync services

iCloud Drive and other sync services

Note: this is written with macOS 10.10 and 10.11 in mind.

Fresco supports iCloud Drive (introduced in macOS 10.10) and similar services that operate on the idea of having a local folder that is kept in sync between multiple devices. Examples of other such services are Dropbox, OneDrive, Box Sync and Google Drive.

Fresco should be able to work with any such sync or cloud service, as long as the service keeps local copies of the files on the Mac.

Fresco tracks filesystem changes so any sync related change to local files and folders will be detected.

iCloud Drive differs slightly from the other sync services mentioned, as it, to some extent tries to present the iCloud Drive as a cloud-only drive, but in reality there are still local copies of the files on the disk.

Note: Dropbox has also been tested and appears to work without any issues.

Note: deselect and reselect a folder in Fresco to trigger an explicit refresh of the preview listing. This should not be needed but may be useful to know about if sync changes are not properly registered for some reason.

Optimized Storage

Fresco also supports the macOS 10.12 (Sierra) feature of Optimized Storage. Enabling this for your Desktop and Documents folders (to clear up space on your local harddrive) may move files onto iCloud. Such files will need to be downloaded when accessed, which could result in delays or access failures, if the internet connection is slow or non-working.

This upload and download behavior is hard to test, so Frescos handling of it could be buggy or broken. Bug reports are much appreciated.


No user information is currently being collected.

Dragging or resizing an image (in the adjuster area) is jerky

Make the adjuster area smaller, so that the actual size of the image being moved around becomes smaller. What matters is the images actual on screen size in pixel, whether its fully visible or not.

Fresco has some optimizations to make zooming (in & out) smoother when running macOS 10.7 (and later), 10.6 on the other hand does not and will be more jerky, especially when working with vector images.

Also note that zooming complex vector images to very large sizes can result in stuttering and slowdowns.

To alleviate stuttering, each vector image is given a number of pre rendered bitmaps, at different sizes. These bitmaps make zooming fast as long as there is a sufficiently large bitmap that can be downscaled to fit the size used in Fresco. When going beyond the largest bitmap size macOS is forced to re-render the vector image to a bitmap at every zoom step. Re-rendering a complex vector could take seconds or notable fractions of a second which is to slow to get a smooth animation.

It is also possible to run into VRAM size limits, this should be rare but can be triggered under certain circumstances like the one below:

Moving the image should now become very jerky as the Mac is forced to swap parts of the image in & out of the GPU on each animation frame—this is similar to VM (Virtual Memory) trashing.

One or more desktops show the wrong image after a reboot (part 1)

MacOS will revert to using the default desktop picture if it fails to find the image that was assigned to the desktop. This normally occurs when an assigned image, at a later date, gets deleted, renamed or moved.

Fresco can both increase and decrees the risk of encountering this issue. Fresco has its own internal store of Applied images which is separate from saves and the original images, so deleting either will have no adverse effects. Certain ways of using Fresco, can on the other hand, result in Applied images being deleted while they are still in use by macOS. Part 2 discusses why this can occur and how to avoid it.

The simplest fix is to select a save and re-apply it or select an image and apply it.

If images were re-applied and the issue re-ocurs after a reboot or login, then try one of the solutions below. None of these approaches are sadly guaranteed to work. The solutions below have been compiled from various forum discussions, no official or fool proof solution appears to exist.

Possible fixes

1 There are a number of different files that can be deleted to try to reset macOS to a working state. When doing this: remove the files, reboot and re-apply images to each desktop (on each display), then reboot again to see if the new images stay in place.

1a Remove the following files to clear all information about which image is used on which desktop:

Removing ~/Library/Caches/ will force macOS to refresh certain information, this may include desktop picture related settings. Note: ensure that System Preferences is not open when deleting this file.

1b The following three files store information about which desktops are in use on each display. Note: removing these will also reset the Dock configuration.

2 Use System Preferences → Desktop & Screen Saver → Desktop to set all desktops (using the stock images), then reboot. This may help macOS to get back to proper desktop settings.

3 On macOS 10.9 or later, disable System Preferences → Mission Control → Displays have separate Spaces, reboot, set desktops, re-enable Displays have separate Spaces, reboot.

Fixes primarily mentioned for macOS 10.8 and its “desktop reverts to default desktop picture” issues

4 Macs that have both an integrated and a dedicated GPU (e.g. some MacBook Pros) may need to have their desktop images set in both modes. Modes can be toggled using gfxCardStatus or by enabling/disabling System Preferences → Energy Saver → Automatic graphics switching.

5 Restarting the Dock using the Terminal command killall -HUP Dock should reload the desktop picture on macOS 10.7-10.11, on 10.6 it only restarts the Dock and on 10.12 nothing at all appears to happen.

It may be possible to trigger a reload of the desktop picture by temporarily changing display resolution, sleeping & waking the mac, attaching & detaching a monitor or toggle the mac between the integrated and dedicated GPU if it has both.

Note: this should only have an effect if the issue is that macOS fails to use the assigned image, missing images can't become non-missing.

6 Selecting System Preferences → Security & Privacy → General → Disable Automatic Login (i.e. require login at reboot) may make a difference.

There may also be a difference between rebooting directly vs logging out and then rebooting.

7 Add the image folders used, to System Preferences → Desktop & Screensaver using the plus button.

8 Very large images, e.g. some camera images, may take to long to load and result in the usage of the default desktop picture. In this case it may help to create a scaled down version, that is closer to the actual pixel size of the display.

One or more desktops show the wrong image after a reboot (part 2)

Adhere to the rules below to avoid future issues.

On macOS 10.6 you need only follow rule 1.
Following rule 1 will also be sufficient if you start out with (and continue to use) a fixed set of desktops.


In rare cases it may also be worth looking into doing some Advanced Adjustments.

Read on if you want to understand the reasons for these rules.

Fresco creates one (app private) image file per display when an Apply is done. Placing images on desktops using macOS, allows for only minor scaling adjustments. These aim only at making the image “fit” on a display. Having Fresco create its own images allows for anything that can be desired, to be put on screen, e.g. screen spanning panoramas, collages of images or mirrored versions of images.

A drawback of needing to create new images rather than simply pointing to ones already on disk (like Desktop & Screen Saver does) is that Fresco needs to remove old “unused” images to avoid filling up the disk. Determining if an image is “unused” is fairly tricky as macOS doesn't give Fresco any direct way to check the assignment of images to desktops.

Fresco deals with this in two ways:

Tip: rebooting is helpful. As the images actually in use, will be updated with new last accessed times as macOS reloads them.

Advanced Adjustments

Actively using a large number of desktops, on a large number of displays, could result in exceeding the limit of images kept on disk. Exceeding the limit, will force some images that are in use, to be deleted, resulting in some incorrect desktop pictures at reboot.

You can use the Terminal commands below to increase (or decrease) the maximum number of images kept. Remember to quit Fresco before changing any settings.

Use write to set a new numerical value, use read to check what value (if any) is currently set and use delete to reset the value to its default. Type man defaults in Terminal to read about the defaults command.

   defaults write com.glimmir.Fresco maxNoOfDesktopSectionsInSpaces ...
   defaults read com.glimmir.Fresco maxNoOfDesktopSectionsInSpaces
   defaults delete com.glimmir.Fresco maxNoOfDesktopSectionsInSpaces

Rebooting or running the command below, may be needed on macOS 10.9 (or later) for the changes to take effect.

   killall -SIGTERM cfprefsd

The default value of maxNoOfDesktopSectionsInSpaces is 80.

Note: decreasing the value will result in images being discarded, at the next Apply, if the new limit is smaller than the number of images currently kept.

Don't increase maxNoOfDesktopSectionsInSpaces more than what is necessary as it will increase disk usage. Setting the value to 100 when using 1920×1080 sized displays will result in a disk use of roughly 400MB (100×4MB) when all 100 entries have been created. Using 4K displays will increase this to 1.6GB (1600MB) as 4K displays have twice the number of pixels (3840×2160) in both directions.

Apply click has no effect

Using both Fresco and System Preferences → Desktop & Screen Saver → Desktop can sometimes result in odd glitches when viewing or changing desktops using System Preferences. A display may e.g. be switched to use a solid color as its background. Observations also show that this kind of glitch may trigger macOS to no longer accept Apply clicks.

Solution: simply change the image on the affected display once, using System Preferences, after this Fresco will again work as expected.

Tip: use only Fresco to change desktop images and avoid opening System Preferences → Desktop & Screen Saver → Desktop.

Note: this is probably triggered by macOS failing to find a deleted image, as discussed in One or more desktops show the wrong image after a reboot part 1 and part 2.

The names of files, folders or parts of filesystem paths are wrong

This will mainly affect the folder-tooltip that shows the filesystem location of folders in the image sources area.

Fresco will show folder names the same way as shown in Finder. The raw filesystem names and the names in Finder are usually the same but differ for certain things e.g. the names of the stock folders in your home folder (if your not using English as your preferred language) as well as the app folders shown on the iCloud Drive.

This is only works for paths to locations that actually exist. A (image source) location can fail to exist if the folder added to Fresco has been deleted. A folder located on a drive that's not plugged in will also be treated as non-existing.

Fresco will display the appropriate names, in a file path, for the part of the path that does exist. Any folders in the non-existing part will get the raw filesystem name.

"Show On All Desktops" is disabled

This command is disabled on macOS 10.6 as the OS only supports setting a desktop picture per display rather than per desktop (Space), so there is no point in moving Fresco from desktop to desktop.

Is there P3 color support?

No, not at this time (July 2017).

Even if you do have a Mac that can display P3 colors, you're unlikely to have access to many P3 color images (assuming your not a professional photographer) as: