Virtual Desktops for ChromeOS

This extension provides virtual desktop capabilities for ChromeOS, and some more.

Current Features

• Create virtual desktops. Move windows between them via keyboard shortcuts.
• Position windows on a tiling grid layout via keyboard shortcuts.

Note: to use the keyboard shortcuts (which is highly advisable), go to this extension's settings and use the "Keyboard shortcuts" button to set a shortcut to launch this extension. Alternatively, use the default shortcut of [Shift]-[Alt]-d.

The following keyboard commands are available (where [Modifier] is any modifier from Shift, Ctrl, Alt and Command, as per your preference, and [Shortcut] is your configured keyboard shortcut, which is [Shift]-[Alt]-d by default):

• [Shortcut] q: Move the current window to the top left (other position/size keys are displayed in the popup).
• [Shortcut] [Modifier]-q: Extract the current tab from the current window, and move it to the top left (other position/size keys are displayed in the popup).
• [Shortcut] [Left]: Switch to the previous virtual desktop.
• [Shortcut] [Modifier]-[Left]: Send the current window to the previous virtual desktop.
• [Shortcut] [Modifier]-[Right]: Send the current window to the next virtual desktop.
• [Shortcut] [Right]: Switch to the next virtual desktop.

Installation

To install the extension, you can either visit its page on the Chrome Web Store or run the included build_using_closure_compiler.sh script (which requires the Closure compiler) and then load it into Chrome as an unpacked extension.

How It Works

In this section, the inner workings, and which features of Chrome and ChromeOS make this possible, will be explained. If you do not care for technical details, I'd recommend you skip it.

Browser Action Icon

The browser action icon is actually created via a <canvas> element. This allows rendering the desktop number on the icon on-the-fly without needing one image file per supported desktop.

Moving Chrome Windows

To reposition an existing window, the chrome.windows API is used. However, one can't just call chrome.windows.update() on an existing window and expect the position and size to "just work"! The problem is that especially on X11, the window manager will add window borders and title bars to the Chrome-specified target window size. So to actually achieve the desired position, the following approach is taken:

• Position the window to the desired location via chrome.windows.update().
• Wait a little to let the window manager actually perform the update. The callback of chrome.windows.update() is invoked after Chrome successfully requested the size change from the window manager, but before the window manager actually performed the action! In fact, on X11, the window manager can even silently ignore the request, so there is no safe way for Chrome to just "wait till the window manager is done".
• Query the actual position and size of the window. This will return the content area's position and size, excluding the title bars and borders.
• Observe that the new left and top coordinates of the window have been shifted down and right to make space for borders and title bars.
• Perform another chrome.windows.update(), compensating for the additional space.

Note that this will allow a window to overlap its neighboring window's borders. This is intentional to save some space on the screen. It should not be possible for a window to actually overlap into a neighboring window's content area.

No Chrome permissions are required for this action.

Extracting Tabs to New Windows

To turn an existing window into a tab, the chrome.windows API provides a chrome.windows.create() method that can create a new window using the tabId of an existing tab. To find the tabId of an existing tab, chrome.tabs API provides a chrome.tabs.query() method that can ask for the active tab in the currentWindow.

There are some pitfalls here too, though:

• On X11, chrome.windows.create() has a similar but not identical behavior regarding the requested vs final window size. To keep the code free from special cases, we instead create the window without a size specification, and move it into place using chrome.windows.update() as in the previous section.
• By default, creating a new window using the tabId of an incognito window will not become incognito, thus leaking history. To work around this, simply pass throgh the tab's incognito property to the chrome.windows.create() call.

No Chrome permissions are required for this action.

Managing Virtual Desktops

There is currently no way in ChromeOS to manage virtual desktops a window is on. So how can we possibly do this? Essentially using the same approach existing software can use to provide the same feature on Windows.

Essentially, what this means is:

• To switch virtual desktops, all windows not on the current desktop will be minimized, and all windows on the target desktop will be restored.

Of course, there are pitfalls when doing this too:

• ChromeOS does not seem to remember previous window size and positions of a window. Thus we have to remember these before minimizing a window when switching away from its desktop.
• ChromeOS will move other windows out of the way when restoring windows. To work around this, we first perform all minimizing/restoring operations without specifying a target size, and then run a second round setting the window positions.
• Setting window positions needs to use the above mentioned workaround to chrome.windows.update()'s flaws as mentioned above.
• You don't want to lose information about the desktops when rebooting ChromeOS. So the internal information containing each window's desktop, position and size is persisted into localStorage.

No Chrome permissions are required for this action.

Limitations

• Due to X11-specific workarounds, window positioning and desktop switching is somewhat slow. In later versions, these workarounds might be disabled where not necessary.
• Only Chrome browser windows can be managed. Extensions have no access to windows of apps - and apps have no access to windows of other apps.
• Alt-Tabbing to a window on another virtual desktop will fetch this window to the current desktop. Detecting this and instead switching to the desktop this window is on - like many X11 window managers do - may not be possible on ChromeOS, as onFocusChanged events will be raised during the Alt-Tabbing already and not just when releasing the keys like what happens on most X11 window managers.
• Empty virtual desktops are not allowed. The problem is that a Chrome window is required to receive deskop switch related keyboard shortcuts, and thus an empty desktop would no longer allow you to switch to a non-empty one. Thus empty desktops will be skipped when switching between desktops, and closing the last remaining Chrome window on a desktop will automatically switch to another, non-empty, desktop.
• By default, this extension is not active in incognito windows. However, it is safe to enable it there, which you can do on chrome://extensions.

License

The code is released unser the Apache 2.0 license. See the LICENSE file for more details.

This project is not an official Google project. It is not supported by Google and Google specifically disclaims all warranties as to its quality, merchantability, or fitness for a particular purpose.