pcbnew regression: Mirroring graphics items changes snapping point to selection center after operation, if not moved before
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# Description
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Duplicating a set of graphics items and mirroring that set used to (in 7) retain the snapping point. In 8, after completing the mirror operation the selection is suddenly 'held' by what looks like a center point.
# Steps to reproduce
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1. Edit a footprint
2. Select graphics items (for example courtyard)
3. Use `D` to duplicate
4. Immediately right-click and select Mirror
Note that if the duplicate is moved before mirroring the problem does not appear.
# KiCad Version
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```
Application: KiCad Footprint Editor x86_64 on x86_64
Version: 7.99.0-4149-g9db1dd5ec5, release build
Libraries:
wxWidgets 3.2.4
FreeType 2.13.2
HarfBuzz 8.3.0
FontConfig 2.15.0
libcurl/8.5.0 OpenSSL/3.2.0 zlib/1.3 brotli/1.1.0 zstd/1.5.5 libidn2/2.3.4 libpsl/0.21.2 (+libidn2/2.3.4) libssh2/1.11.0 nghttp2/1.58.0
Platform: Arch Linux, 64 bit, Little endian, wxGTK, Wayland, KDE, wayland
Build Info:
Date: Jan 1 2024 20:45:27
wxWidgets: 3.2.4 (wchar_t,wx containers) GTK+ 3.24
Boost: 1.83.0
OCC: 7.7.2
Curl: 8.5.0
ngspice: 41
Compiler: GCC 13.2.1 with C++ ABI 1018
Build settings:
KICAD_USE_EGL=ON
```
issue