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fix(windows): prevent mouse click-through in fullscreen for transparent windows#5195

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leaanthony merged 2 commits into
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fix/4408-fullscreen-clickthrough
May 31, 2026
Merged

fix(windows): prevent mouse click-through in fullscreen for transparent windows#5195
leaanthony merged 2 commits into
masterfrom
fix/4408-fullscreen-clickthrough

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@leaanthony

@leaanthony leaanthony commented Apr 20, 2026 •
edited by coderabbitai Bot
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Summary

  • Remove WS_EX_TRANSPARENT alongside WS_EX_DLGMODALFRAME when entering fullscreen mode to prevent layered window pass-through
  • Return HTCLIENT from WM_NCHITTEST while in fullscreen mode to force mouse event capture regardless of alpha-based hit-testing
  • Add test verifying the fullscreen hit-test logic

The root cause: When Frameless and BackgroundType: Transparent are both set, the window has WS_EX_LAYERED which uses alpha-based hit-testing. In fullscreen, transparent pixels (alpha=0) pass mouse events through to underlying windows. By removing WS_EX_TRANSPARENT and overriding WM_NCHITTEST to return HTCLIENT, all mouse events are captured.

Fixes #4408

Test plan

  • TestFullscreenNCHitTestReturnsHTClient — verifies hit-test returns HTCLIENT in fullscreen, doesn't in normal mode
  • GOOS=windows go build ./pkg/application/ — compiles cleanly
  • Manual testing: Create window with Frameless: true and BackgroundType: application.BackgroundTypeTransparent, enter fullscreen, verify clicks are captured

Summary by CodeRabbit

  • Bug Fixes

    • Fixed mouse click-through issue in fullscreen mode when using Frameless + Transparent window options on Windows.

  • Tests

    • Added test coverage for fullscreen click-through behavior.

fix(windows): prevent mouse click-through in fullscreen for transpare…
5142aa3 
…nt windows

When a window with both Frameless and BackgroundType (transparent)
options enters fullscreen, mouse clicks pass through to underlying
windows because WS_EX_LAYERED uses alpha-based hit-testing where
transparent pixels don't capture events.

Fix by:
1. Removing WS_EX_TRANSPARENT alongside WS_EX_DLGMODALFRAME when
   entering fullscreen
2. Returning HTCLIENT from WM_NCHITTEST while in fullscreen mode to
   force all mouse events to be captured by the window

Fixes #4408
@coderabbitai

coderabbitai Bot commented Apr 20, 2026 •
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Review Change Stack

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info
⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: f7cec364-94e2-45c6-bab2-a54f7b6f20ec

📥 Commits

Reviewing files that changed from the base of the PR and between dcfce51 and 57f790b.

📒 Files selected for processing (3)
  • v3/UNRELEASED_CHANGELOG.md
  • v3/pkg/application/fullscreen_clickthrough_test.go
  • v3/pkg/application/webview_window_windows.go

Walkthrough

This PR preserves the transparent extended window style during fullscreen and short-circuits WM_NCHITTEST to HTCLIENT while fullscreen; adds a unit test for the hit-test decision and a changelog entry noting the Frameless+Transparent fullscreen click-through fix.

Changes

Fullscreen Click-Through Fix

Layer / File(s) Summary
Hit test capture validation
v3/pkg/application/fullscreen_clickthrough_test.go		 New parameterized test validates shouldCaptureHitTest helper function returns the expected boolean for fullscreen and non-fullscreen cases.
Fullscreen extended style and hit test message handling
v3/pkg/application/webview_window_windows.go		 Extended style preservation during fullscreen now includes WS_EX_TRANSPARENT; WndProc intercepts WM_NCHITTEST when fullscreen and returns HTCLIENT to capture client-area mouse events.
Changelog entry
v3/UNRELEASED_CHANGELOG.md		 Documents the fix for mouse click-through behavior in fullscreen mode with Frameless + Transparent window options (refs #4408).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Suggested labels

Bug, go, Windows, v3, size:M

Poem

🐰 A rabbit hops through code at night,

preserving panes that hid the light,
hit-tests halted, clicks held fast,
Frameless transparent woes are past,
fullscreen now keeps users tight.

✨ Finishing Touches
📝 Generate docstrings
  • Create stacked PR
  • Commit on current branch
🧪 Generate unit tests (beta)
  • Create PR with unit tests
  • Commit unit tests in branch fix/4408-fullscreen-clickthrough

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain main module or its selected dependencies"

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@leaanthony leaanthony changed the base branch from v3-alpha to master April 29, 2026 13:07
@leaanthony leaanthony added this to the v3.0.0-beta.1 milestone May 20, 2026
@leaanthony leaanthony mentioned this pull request May 31, 2026
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@leaanthony leaanthony marked this pull request as ready for review May 31, 2026 07:13
Copilot AI review requested due to automatic review settings May 31, 2026 07:13
@leaanthony leaanthony merged commit ae5abd9 into master May 31, 2026
13 of 17 checks passed
@leaanthony leaanthony deleted the fix/4408-fullscreen-clickthrough branch May 31, 2026 07:13
Copilot AI reviewed May 31, 2026

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Successfully merging this pull request may close these issues.

Fullscreen API click through with certain window options

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@leaanthony