Revert "Fix for #11988 : Drop down menus appear outside of PS and cannot be opened again"

This reverts commit 6ff8537ff4fbd14ca09934cdb2bb987131a7b559. There is a non-trivial conflict
when merging to master, let's redo the commit after the merge so it is clear in history.

src/slic3r/GUI/Plater.cpp

@@ -753,38 +753,10 @@ static wxRichToolTipPopup* get_rtt_popup(wxButton* btn)
     return nullptr;
 }
 
-// Help function to find and check if some combobox is dropped down and then dismiss it
-static bool found_and_dismiss_shown_dropdown(wxWindow* win)
-{
-    auto children = win->GetChildren(); 
-    if (children.IsEmpty()) {
-        if (auto dd = dynamic_cast<DropDown*>(win); dd && dd->IsShown()) {
-            dd->CallDismissAndNotify();
-            return true;
-        }
-    }
-
-    for (auto child : children) {
-        if (found_and_dismiss_shown_dropdown(child))
-            return true;
-    }
-    return false;
-}
-
 void Sidebar::priv::show_rich_tip(const wxString& tooltip, wxButton* btn)
 {   
     if (tooltip.IsEmpty())
         return;
-
-    // Currently state (propably wxWidgets issue) : 
-    // When second wxPopupTransientWindow is popped up, then first wxPopupTransientWindow doesn't receive EVT_DISMISS and stay on the top. 
-    // New comboboxes use wxPopupTransientWindow as DropDown now
-    // That is why DropDown stay on top, when we show rich tooltip for btn.
-    // (see https://github.com/prusa3d/PrusaSlicer/issues/11988)
-
-    // So, check the combo boxes and close them if necessary before showing the rich tip.
-    found_and_dismiss_shown_dropdown(scrolled);
-
     wxRichToolTip tip(tooltip, "");
     tip.SetIcon(wxICON_NONE);
     tip.SetTipKind(wxTipKind_BottomRight);

src/slic3r/GUI/Widgets/DropDown.hpp

@@ -86,8 +86,6 @@ public:
     bool HasDismissLongTime();
 
     static void SetTransparentBG(wxDC& dc, wxWindow* win);
-
-    void CallDismissAndNotify() { DismissAndNotify(); }
     
 protected:
     void OnDismiss() override;