Fixing Fcitx5 Key Release Event Glitches In Sway

Hey there, fellow Linux enthusiasts! Ever found yourself in a tricky situation where your input method editor (IME) seems to be playing hide-and-seek with your keystrokes? Specifically, if you're a Sway user relying on Fcitx5 for your input needs, you might have stumbled upon a peculiar issue: the dreaded missing key release event for certain keys. It's like your computer forgets you've lifted your finger, leading to frustrating repetitive inputs. Today, we're diving deep into this specific problem, dissecting its symptoms, exploring diagnostic insights, and discussing potential pathways to a smoother typing experience. Let's unravel this mystery together and make your Wayland desktop truly yours.

Unraveling the Fcitx5 Key Release Event Mystery

Imagine this: you're working diligently in Sway, typing away, when suddenly, a single press of your Escape key turns into a rapid-fire stream of Escape characters. This isn't just annoying; it can disrupt your workflow, especially in applications where Escape is a critical command. This is precisely the issue at hand: Fcitx5 appears to be missing the key release event for specific keycodes, particularly keycode=9 (which is typically your Escape key) when running under the Sway Wayland compositor. Other keys, however, seem to behave perfectly, registering both key pressed and key released events without a hitch. This selective amnesia from Fcitx5 is what makes this bug so intriguing and, frankly, quite bothersome. We need to understand why this is happening, especially since the underlying system is registering the release.

To confirm that the issue isn't with the hardware or Sway itself, a useful tool called wev (Wayland event viewer) comes into play. When wev is used to monitor keyboard events, it clearly shows that the keycode 9 (our Escape key) does generate both a state: 1 (pressed) and a state: 0 (released) event. This is crucial information! It tells us that Sway is correctly receiving and propagating the physical key release signal. The problem, therefore, isn't that the event isn't happening, but rather that Fcitx5 isn't receiving or processing it correctly. This immediately shifts our focus to Fcitx5's internal handling of Wayland input events. To further solidify this theory, even remapping keycode 9 to a different letter, like e, using xkb still resulted in the same behavior within Fcitx5: repetitive 'e's, indicating the issue isn't tied to the Escape function itself but to how Fcitx5 handles that particular keycode's release event. This suggests a deeper integration problem or a bug within Fcitx5's Wayland frontend. Understanding this distinction is the first critical step in troubleshooting, as it narrows down our investigation from the entire system to a specific component within the input method framework. The impact on user experience is significant, transforming a simple keystroke into an irritating obstacle course, highlighting the importance of robust input handling in any desktop environment, especially one as dynamic as Wayland with Sway. Without proper input handling, the fluidity of interaction that Wayland promises can be severely compromised, making this a high-priority issue for affected users.

Diving Deep into the Diagnostics: What fcitx5-diagnose Reveals

When faced with complex input issues like this, the fcitx5-diagnose command is your best friend. It gathers a wealth of system and Fcitx5 specific information, helping us piece together the puzzle. Let's break down the key insights from the diagnostic output, translating technical jargon into actionable understanding. This powerful tool provides a snapshot of your environment, allowing us to identify potential misconfigurations or conflicting settings that might contribute to the Fcitx5 key release event problem in Sway.

First, the System Info section tells us you're running on Manjaro Linux with a recent kernel (Linux COOLLINUX 6.17.13-1-MANJARO). The most important takeaway here is XDG_SESSION_TYPE='wayland'. This confirms we're squarely in a Wayland session, which means Fcitx5 should ideally be using its native Wayland input method frontend rather than relying on X11 compatibility layers. This foundational detail immediately informs our troubleshooting approach, guiding us to focus on Wayland-specific configurations and potential interactions between Fcitx5 and the Sway compositor. The Manjaro distribution and recent kernel version suggest a fairly up-to-date system, which can be both a blessing and a curse: blessings because newer software often has bug fixes, and a curse because new bugs can sometimes be introduced in fresh updates, making it essential to keep an eye on recent changes.

Moving on to the Environment details, we see some interesting points. While DISPLAY=':0' is set, it's typically ignored in a pure Wayland session where WAYLAND_DISPLAY='wayland-1' takes precedence. More notably, fcitx5-diagnose flags missing XMODIFIERS, QT_IM_MODULE, and GTK_IM_MODULE environment variables. These are traditionally important for X11-based applications to properly interact with input methods. While Wayland applications can use native Wayland input protocols, many applications still rely on these environment variables, or their respective toolkits do. The warnings suggest that some applications might not be leveraging Fcitx5's Wayland frontend as intended, potentially falling back to less integrated input methods or encountering issues. For example, the gtk-im-context-simple or QWaylandInputContext classes are being used, which can work, but the missing QT_IM_MODULE=fcitx and GTK_IM_MODULE=fcitx might indicate that a consistent Fcitx5 integration across all applications is not fully established. This discrepancy between Wayland's native input and toolkit-specific environment variables often leads to subtle bugs that manifest as intermittent input issues. Even if the Wayland compositor is sending the event, if the application isn't correctly configured to receive Fcitx5's input, or if Fcitx5 isn't properly hooked into the toolkit's Wayland IM module, issues like missing key release events can occur. This requires careful attention to ensuring the environment is set up for optimal Fcitx5-Wayland integration, not just for the applications, but for Fcitx5 itself.

The Fcitx State section confirms that Fcitx 5.1.17 is running (PID 246347), and fcitx5-remote is working, indicating the core Fcitx5 daemon is healthy. The D-Bus interface shows several InputContext entries for programs like firefox and kitty, all using frontend:wayland_v2. This is excellent news, as it verifies that Fcitx5 is indeed attempting to use its modern Wayland frontend. However, the presence of cap:72 and cap:100000072 indicates different capabilities for these input contexts. While generally a good sign, the precise interaction between Fcitx5's Wayland frontend and Sway's input handling for these capabilities can sometimes introduce edge cases or bugs. The varying cap values could signify different levels of support or modes, potentially leading to inconsistent behavior for certain key events, such as the key release event for keycode 9. This further reinforces the idea that the problem is not in Fcitx5's ability to run or communicate, but in a specific interaction within its Wayland input processing. The version 5.1.17 is relatively recent, suggesting it should ideally have good Wayland support, yet the issue persists, pointing towards a deeper, perhaps newly introduced, bug or a very specific environmental factor unique to this setup.

Crucially, the Log section reveals a crash log (/home/user/.config/fcitx5/crash.log) from Fcitx 5.1.17 with Signal No.: 11 (a segmentation fault). The stack trace points directly to /usr/lib/fcitx5/libwlfrontend.so, specifically within functions like _ZN5fcitx13AddonInstance8findCallERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE+0x12 and other related calls within libwlfrontend.so. This is the smoking gun! A segmentation fault within the Wayland frontend library strongly suggests a bug in Fcitx5's implementation of the Wayland input protocol, especially concerning how it handles certain events or conditions. The crash occurs in the findCall method of AddonInstance, implying an issue when a Wayland input event triggers a call to an addon, and something goes wrong during that dispatch. This could be due to unexpected data for keycode=9, a timing issue specific to Sway, or an unhandled state transition when the key is released. This crash log doesn't directly say