AltTabber

AltTabber started back in the Windows 7 days out of frustration with managing a large number of windows. There were no good virtual desktop implementations, and the taskbar was getting ever more annoying compared to ancient versions of Windows. Additionally, I started having more and more monitors connected, and it was getting a bit out of hand to quickly identify "the Visual Studio that's on the 3rd monitor".

The goals of this project were to have a hotkey activation, similar to ALT + TAB or Gnome's ALT + F1 / super, which would lay out a grid of all windows present on each monitor in a multimonitor setup. The grid(s) may be filtered with a simple search string. You may activate windows primarily through keyboard use, but mouse is supported. It shall show DWM live thumbnails if Aero is running. It shall be lightweight.

This was successful, but Windows has made things less of a problem as we went from 7 through 8.1 to 11. But I still use it purely because of AltTabber's keyboard-first design, and especially because I can very quickly type n o t e p a d and list all 20 open notepad windows, and I can then figure out where I wanted to go.

This project lives at https://github.com/alzwded/AltTabber/ .

Key bindings and activation

(hotkey refers to the global hotkey associated with AltTabber. By default, it is ALT + key above tab)

action	inputs	comments
open overlay	hotkey or clicking the icon in the notification area	the main bread of the application
close overlay	Esc	exits the overlay without switching to a new window and without exiting
exit the application	Alt-F4	duh
move to other windows	Tab, Shift-Tab, arrow keys, mouse + click, mouse wheel	this doesn't actually switch the window, rather the selection for actually triggering the selection
switch window	Enter, double click, hotkey	switches to the selected window (the one with a red background
help/about	F1
start/stop logging	F2	this is a debug log; it writes it somewhere in %TEMP% in a file with a name like alt????.tmp
search/filter	any printable characters	starts filtering the windows by name and/or image path in order to help find your window among a couple of dozen

Changing the hotkey

The hotkey can be changed from Alt-key above tab by going in the registry under HKEY_CURRENT_USER\Software\jakkal\AltTabber and modifying the modifiers and key values.

The modifiers value is a combination of the values described for fsModifiers here things.

The key value is one of these.

For example, you can set the modifiers value to 3 (Alt + Ctrl) and the key value to 33 (the 3 key). If you didn't catch on, the aforementioned values are numbers in hexadecimal.

If you mess something up, just delete the HKEY_CURRENT_USER\Software\jakka\AltTabber key and the app will make sure to recreate it again from defaults.

If you want to remove this app from your computer forever, remember to also delete that key. No uninstaller is currently provided, and it's unlikely that one will be provided anytime in the future.

That key also contains a flag, resetOnClose, which, if set to 0x00000000, will prevent the AltTabber interface from being reset when you close a window using the context menu. This leaves some dangling slots/thumbnails around, but the resets were getting annoying.

Accessibility

As of version 1.9, AltTabber implements UI Automation. The overview presents the thumbnails as button control types with the invoke pattern. The window title is read when one of these thumbnail buttons comes into view (same text that you see rendered on screen). It is recommended to use AltTabber's builtin keyboard navigation (i.e. TAB, SHIFT+TAB, ENTER and ESCAPE) since that is the code path that was most thoroughly tested in the past decade. Screen reader commands to the tune of "move to next control" and "activate/invoke" control seem to work, but I am not a proficient AT user, so it's hard to judge if I got the UIA provider implementation right.

Accessibility is not thoroughly tested. If you do test it, and it has problems, do let me know. Though I understand both JAWS and NVDA already have a fancy window list builtin, so I'd also like to know why you are here :-).

Getting AltTabber

You should fetch the .exe from Github Releases. You will need some sort of MSVCRT installed, but you must get that from Microsoft. Check the vcxproj's Release x64 configuration to see what toolset it was built with; you'll need the MSVCRT from that era. I have always been in a situation where these were installed already, so I never bothered to figure out exactly which one you need at any given moment in time.

You can build it from source with whatever the version du jour of Visual Studio Community is. If it complains about toolsets or SDKs, just pick whatever your installation came with, this project should have no special requirements w.r.t. the toolchain version. Prefer the Release x64 configuration. The 32 bit configuration has fundamental issues trying to fetch information for 64 bit running applications. Building from source will guarantee you have the appropriate MSVCRT installed as a by-product of setting up the toolchain.

Hacking

This project was a hackjob to begin with, but here is an outline:

• AltTabber.cpp holds the WinMain, message loops, and other plumbing typical of a Windows application. Global variables are declared here.
  • it also contains the complicated code of figuring out which windows need to be shown, what their titles are, and fetching their thumbnails
  • MoveToMonitor: I have had attempts to deal with minimized windows, e.g. to move them from one desktop to another, but many, many programs don't like that. Moving maximized windows around also lead to weirdness.
  • The move to monitor n context menu entries are capped at 10. I hope you don't have more than 10 monitors on your workstation. If you do, let me know how you did it!
  • A global hotkey is installed, per what's specified in the registry (see below)
• Program state is stored in ProgramState_t, of which there should only ever be one.
• The notification icon exists solely to let a user know this thing is running at all. There is no attempt to restore it e.g. after restarting the explorer.exe instance that runs as the shell. And yes, I am aware this usage is universally despised by UX people, but I like to know when something is running without bringing up taskmgr.exe
• Persistent state is stored in the registry under HKCU\Software\jakkal\AltTabber. This is hardcoded. If the key or values are not there, they are initialized from defaults. See Registry.cpp
• Gui.cpp basically contains the window OnPaint function, but also additional layouting to position DWM Thumbnails
  • it still has the icons code path, which is a holdover from Windows 7, where Aero might not have been running. This is no longer applicable on Windows 8+
  • I opted to have a bit OnPaint function which renders the grid, because constantly creating/destroying e.g. MFC controls can get stupid slow and complicate things. We just need to lay out a grid of labels with some space set aside for live thumbnails, it's not that hard to write/maintain
  • PerformSlotting is what lays out the slots in per-monitor grids.
• Log.cpp has the log implementation. Normally, logs go >NUL. Logging must be turned on with the F2 key, which will write the file out to a tempfile. It force flushes after each print, to support re-living the final moments before it goes bang.
• MoveFunctions.cpp contains spaghetti logic dealing with keyboard arrow or mouse movement between grid cells. This makes stuff like using the arrow keys to go cross monitors work.
• MonitorGeom.cpp contains code to figure out where all your monitors are. Windows is a bit like X11, and there is a single giant canvas, with monitors being views on this canvas. Unlike X11, I don't think monitors may be positioned arbitrarily, at least not to my knowledge. I have only tested with monitors whose bounds touch :-) But I have extensively used this with monitors with mismatched resolutions, arranged both vertically and horizontally
• OverlayActivation.cpp contains the code to turn the overlay, and when deactivating, to switch focus to the window you selected. Thumbnails and slots are refreshed when activating the overlay, or when filtering
• A11Y is implemented in UIAutomationProvider.cpp, using the UI Automation interfaces; but:
  • the global ProgramState_t holds a reference to the root provider, if any, in order to ping it when state changed
  • as the main message loop is in AltTabber.cpp, it is created there (upon WM_GETOBJECT being received)
  • There is an atomic int called rebuildingSlots which is used as a mutex (which is not the same thing) in order to prevent access to the slots while they are rebuilding, because UI Automation injects threads in the application. This should be a Mutex, but that is heavy handed when UIA is not running. This appears good enough as I couldn't reproduce seg faults anymore on either high end or low end hardware; if you can, switch this to a mutex.
• Localization: feel free to run this README through Google Translate, and that's all you need to know. HOWEVER...
  • this is probably more important for A11Y. The strings used there are part of the .rc file, so if anyone feels like translating them, they can. But there's not much there; there's some cheesy help text explaining keyboard bindings, and the F1 dialog, and context menu strings. Not sure it's worth the effort, honestly. But if you want to do it, read up on how to add other languages to the string tables in resource files.
  • also, it's probably important for RTL languages. Never tested with those, I don't live in an environment where I encounter these. The app is UTF-16/UCS-2 and uses native windows API, it should work question mark? Dunno.
  • for the most part, you're only ever seeing strings forced upon you by literally all other applications. You might get an error message complaining the hotkey is already registered when starting this up.

A large amount of windows need to be filtered out. You'd be surprised how many eye candy rich apps have a ton of floating BS to make them look pretty. Windows 8 added cloaking to have an intended way to do this. Cloaked windows participate in DWM rendering, but they are meant to be ignored for all intents and purposes, i.e. all the BS that older applications used to do for eye candy effects.

Accessibility isn't terribly well tested, but screen readers can "see" it, and navigation works. If you add new "features", make sure they are accessible. Narrator is installed on all Windows machines, turn it on with WIN + CTRL + ENTER, you don't really need to do anything special to check it reads out everything that's going on.

Disclaimer

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.