Q-W2: split bank_panel.cpp (3459 LOC) into eight shell/panel TUs — reasampler::panel internals, per-seam public headers, shim retired; zero behavior change, 60/60 green

src/shell/panel/panel_window.h

@@ -0,0 +1,42 @@
+#pragma once
+// panel_window — the window-lifecycle seam of the docked bank panel (Q-W2 split of
+// bank_panel.h; M5, Wave A). REAPER-facing shell: the .cpp owns a SWELL dialog
+// (IDD_BANK_PANEL) docked via DockWindowAddEx / undocked via DockWindowRemove,
+// toggled open/closed, plus the OS drop-target opt-in (S8) and the dialog proc that
+// routes messages to the input/drag/render seams. The panel itself NEVER inserts
+// into the arrange or mutates the project (CONTEXT.md §load-bearing principle).
+//
+// The header is REAPER-free: main.cpp drives the panel through these free functions,
+// passing the live session so the panel reads the current bank. All SWELL / LICE /
+// PCM_source use is confined to the shell/panel/ .cpp seams.
+
+namespace reasampler {
+
+class ReaSamplerSession;
+
+// Wires the panel into main.cpp's lifecycle. Called once after the API pointers
+// are loaded, BEFORE the toggle action is registered. `session` must outlive the
+// panel (it is the extension-lifetime g_session). Stores the session pointer the
+// panel reads on every repaint; does not create the window yet.
+void bankPanelInit(ReaSamplerSession* session);
+
+// Toggles the docked window: creates+docks it if hidden, hides+undocks it if
+// shown. Bound to the "toggle bank panel" action. Safe to call before the first
+// timer tick.
+void bankPanelToggle();
+
+// Whether the panel window is currently open/visible. Feeds the action's
+// checked-state (toggleaction) so REAPER shows a tick next to the menu entry.
+bool bankPanelIsOpen();
+
+// Requests an immediate repaint of the panel if it is open. A no-op when the panel
+// is closed (safe to call unconditionally). Called by the actions layer after a
+// mode change so the footer [Arrange|Design] toggle reflects the new mode without
+// requiring a hide/reshow.
+void bankPanelInvalidate();
+
+// Tears the panel down on extension unload: destroys the window and releases any
+// cached thumbnails / PCM handles. Mirror of bankPanelInit; safe if never opened.
+void bankPanelShutdown();
+
+}  // namespace reasampler