Keep the Design tab's Bodies right-click menu open on Linux

src/slic3r/GUI/CAD/DesignPanel.cpp

@@ -3363,9 +3363,10 @@ DesignPanel::DesignPanel(wxWindow* parent)
     // been promising this right-click since before it existed.
     m_parts->on_menu = [this, apply_body_row](int row, const wxPoint& screen) {
         apply_body_row(row);   // unconditional — see above
-        // Let the modal menu take the loop after this handler returns — same CallAfter as the
-        // sketch path, which learned it the hard way.
-        CallAfter([this, screen] { show_offer_menu(screen); });
+        // From inside the event, as the feature rows do, never CallAfter'd: wxGTK sends the
+        // context menu on the right PRESS, and a menu GTK pops after that event has finished
+        // has no trigger time, so the button's release closes it the moment it opens.
+        show_offer_menu(screen);
     };
     // Renaming a BODY names the body itself. It does NOT rename the feature that created it:
     // an Extrude, a Cut and a Fillet all land on one body, so source_feature is one operation in

src/slic3r/GUI/CAD/DesignRowList.hpp

@@ -77,7 +77,8 @@ public:
     // the selected one.
     std::function<void(int row, int id)>              on_action;
     // Context menu on a row, at a screen position; the row under the pointer is selected first,
-    // unless the list is non-selectable.
+    // unless the list is non-selectable. Pop the menu from inside the call: wxGTK sends it on the
+    // right press, and a menu deferred past that event closes on the button's release.
     std::function<void(int row, const wxPoint& screen)> on_menu;
     // The editor committed `name` for `row`, trimmed and never empty (an empty commit cancels).
     // Runs after the editor's own events have finished, so the owner may rebuild the rows here.