[mertalp-ulus]

References #116.

Adds four C++ TestServer::mouseDoubleClick overloads matching the existing click API: item center, relative position, relative position plus pixel offset, and button/modifiers.

Qt Quick receives a complete press → release → press → double-click → release gesture. The first release can update selection before confirmation. Events use the target's window and global coordinates, correct released-button masks, and increasing timestamps that separate explicit gestures without sleeps or event-loop pumping in the backend.

Missing targets, invalid button/modifier masks, an already-held button, and unsupported backends report executor errors without starting a partial double-click. Calls enqueue work; callers must wait for an observable application result.

Scope and compatibility

• Implemented for the C++ API with Qt Quick.
• Qt Widgets inherits the default unsupported Events::mouseDoubleClick implementation.
• RPC double-click methods are not registered; RPC and Widgets gestures remain follow-ups.
• The optional virtual method preserves source compatibility for existing backends. Binary consumers and backends must be rebuilt.

Validation

Tested source: 173dc4c38873fbc9f952e1ab697ba1927b05cc15.

• Windows/MSVC 14.50, static builds: all four CTest suites pass on Qt 6.11.0 and 6.11.1.
• Qt 6.11.0: the ten-case GUI gesture suite passes 100 consecutive repetitions.
• Command/GUI coverage includes argument forwarding and rejection, ordinary-click negative control, native Qt positive control, repeated TapHandler gestures, later drag/key input, transformed coordinates, and target destruction.
• New global-coordinate regression covers moved windows and fractional transformed positions. It failed with the previous cursor-derived coordinates and passes with explicit target coordinates.
• Windows/Qt 6.11.0 shared build: Core, QtQuick, QtWidgets, and enabled examples build; installation and the installed BasicStandalone example build pass.
• A consumer linked to the installed Core DLL successfully invokes all four overloads. Shared tests are disabled, matching the upstream shared-build configuration; GUI behavior is covered by the static test builds.
• clang-format 11.1.0 passes on all changed C++ files.

Upstream Qt 5.15.2, Qt 6.9.2/6.10.3, Linux/macOS, and their shared/install configurations remain unverified pending upstream CI.

[mertalp-ulus]

Hi @faaxm ,

This PR is ready for review and adds four C++ double-click overloads for Qt Quick. Local Windows tests passed on Qt 6.11.0 and 6.11.1; Qt 6.11.0 also passed 100 gesture-suite repetitions and shared-build, installation, and consumer checks. RPC and Widgets support remain follow-up work.

Could you please approve the pending workflows so the broader Qt/platform matrix can run?

Thank you!