Merge pS-ga-paneltoggle: repaint panel mode toggle on Design/Arrange action

src/actions.cpp

@@ -251,6 +251,7 @@ void doToggleMode() {
     if (target.empty()) return;  // no modes to cycle to (degenerate)
     applyMode(g_session->view(), target, nullptr);
     persistViewState();
+    bankPanelInvalidate();  // repaint the footer [Arrange|Design] toggle immediately
 }
 
 // Direct jump to a named mode. applyMode is a no-op (returns false, no mutation) if
@@ -258,6 +259,7 @@ void doToggleMode() {
 void doActivateMode(const std::string& modeId) {
     applyMode(g_session->view(), modeId, nullptr);
     persistViewState();
+    bankPanelInvalidate();  // repaint the footer [Arrange|Design] toggle immediately
 }
 
 // Tag the selection's leaves into `modeId`, then reapply so the change is immediate.

src/bank_panel.cpp

@@ -3435,6 +3435,10 @@ void bankPanelToggledBanksFullHeight() {
     setFullHeight(BankPanelFullHeight::BanksOnly);
 }
 
+void bankPanelInvalidate() {
+    if (g_panel.hwnd) InvalidateRect(g_panel.hwnd, nullptr, FALSE);
+}
+
 void bankPanelShutdown() {
     closePanel();
     deinitPreview();

src/bank_panel.h

@@ -117,6 +117,12 @@ void bankPanelToggledPoolFullHeight();
 // Bound to the "banks full-height" action. Requests a repaint.
 void bankPanelToggledBanksFullHeight();
 
+// 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();