fix(windows): Fullscreen click-through with Frameless + Transparent background

[leaanthony]

Summary

• Fix fullscreen click-through on Windows when using Frameless: true with BackgroundTypeTransparent
• Remove WS_EX_TRANSPARENT extended style flag when entering fullscreen to capture mouse events
• Restore original style when exiting fullscreen

Fixes #4408

Root Cause

When a window is configured with Frameless: true and BackgroundType: BackgroundTypeTransparent, Wails sets WS_EX_TRANSPARENT | WS_EX_LAYERED on the window's extended style. The WS_EX_TRANSPARENT flag causes Windows to pass mouse events through the window.

The fullscreen() function preserved this flag when entering fullscreen mode - it only removed WS_EX_DLGMODALFRAME but kept WS_EX_TRANSPARENT, causing clicks to pass through to underlying windows/applications.

The Fix

Modified fullscreen() in webview_window_windows.go to also remove WS_EX_TRANSPARENT when entering fullscreen:

// Before:
w.previousWindowExStyle & ^uint32(w32.WS_EX_DLGMODALFRAME)

// After:
w.previousWindowExStyle & ^uint32(w32.WS_EX_DLGMODALFRAME|w32.WS_EX_TRANSPARENT)

The unfullscreen() function already correctly restores w.previousWindowExStyle, so the original click-through behavior is preserved when exiting fullscreen.

Test Plan

• Create a Wails app with Frameless: true and BackgroundType: BackgroundTypeTransparent
• Enter fullscreen mode using the HTML5 Fullscreen API
• Verify mouse clicks are captured by the fullscreen element (not passed through)
• Exit fullscreen mode
• Verify click-through behavior is restored (if originally enabled)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Fixed an issue on Windows where mouse clicks could pass through frameless fullscreen windows with transparent backgrounds, restoring reliable user interaction with the app window.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Walkthrough

A Windows-specific fix: the fullscreen() path now clears additional extended window styles (WS_EX_TRANSPARENT and WS_EX_LAYERED alongside WS_EX_DLGMODALFRAME) to prevent mouse click-through when Frameless and BackgroundTypeTransparent are both used.

Changes

Cohort / File(s)	Change Summary
Changelog v3/UNRELEASED_CHANGELOG.md	Added a Fixed entry documenting the Windows fullscreen click-through fix for Frameless + BackgroundTypeTransparent.
Fullscreen implementation v3/pkg/application/webview_window_windows.go	In fullscreen(), removed WS_EX_TRANSPARENT and WS_EX_LAYERED from the previous EXSTYLE mask (in addition to WS_EX_DLGMODALFRAME) so mouse events are captured in fullscreen; added explanatory comments referencing the click-through issue.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• [v3] fix: fullscreen, unfullscreen, unminise and unmaximise window events … #4130: Modifies the same fullscreen() function (v3/pkg/application/webview_window_windows.go) to add fullscreen/unfullscreen event emissions — related work in the same code area.

Suggested labels

Bug, Windows, v3, v3-alpha, size:XS

Poem

🐰
Frameless and transparent met the night,
Clicks slipped past out of sight.
I nudged a flag, now events stay near —
Fullscreen holds the cursor dear. ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main fix: addressing fullscreen click-through issues when Frameless and Transparent background are enabled on Windows.
Description check	✅ Passed	The description covers the summary, root cause analysis, fix implementation, and test plan. While the description does not use the exact template structure, it provides all essential information needed to understand the PR.
Linked Issues check	✅ Passed	The PR directly addresses issue #4408 by removing WS_EX_TRANSPARENT and WS_EX_LAYERED extended styles when entering fullscreen, ensuring mouse events are captured as required.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the fullscreen click-through issue: the changelog entry documents the fix, and the code modification addresses the exact problem described in issue #4408.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Untriel]

Just tested this on the latest alpha version. Removing w32.WS_EX_TRANSPARENT does not appear to be enough to fix the click-through behavior.

Additional testing: removing w32.WS_EX_LAYERED does allow the capture of clicks, but is not restored by unfullscreen().

[leaanthony]

Thanks for testing @Untriel! I've pushed a fix that also removes WS_EX_LAYERED in fullscreen mode. Could you test again with the latest commit?

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud