In the side-by-side and top/bottom Before/After layouts a click in the
Before view was mapped to image coordinates through the After view's
rectangle, so the White Balance Selector sampled the wrong point (at Fit,
the photo's edge). The click tools in general_interaction now use the
Before view's image rectangle when the pointer is in the Before view's
pane; the pane decides, since zoomed in an image reaches past its pane.
New headless test tests_before_after.rs clicks the same image point in
the After and Before views (side by side, top/bottom; Fit and 100 %) and
expects the same white balance. Without the fix: Before 8202 K / +116,
After 2710 K / +33.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
