diff --git a/src/slic3r/GUI/MarkdownTip.cpp b/src/slic3r/GUI/MarkdownTip.cpp
index 0ceee2a278..b056ed6364 100644
--- a/src/slic3r/GUI/MarkdownTip.cpp
+++ b/src/slic3r/GUI/MarkdownTip.cpp
@@ -146,8 +146,10 @@ bool MarkdownTip::ShowTip(wxPoint pos, std::string const &tip, std::string const
     if (_tipView->GetParent() == this) {
         wxSize size = wxDisplay(this).GetClientArea().GetSize();
         _requestPos = pos;
+        // Ensure display size is valid
+        if (size.y <= 0) size.y = 600;
         if (pos.y + this->GetSize().y > size.y)
-            pos.y = size.y - this->GetSize().y;
+            pos.y = std::max(0, size.y - this->GetSize().y);
         this->SetPosition(pos);
         if (tipChanged || _hide) {
             _hide = false;
@@ -258,11 +260,15 @@ void MarkdownTip::OnTitleChanged(wxWebViewEvent& event)
         _lastHeight = height;
         height *= 1.25; height += 50;
         wxSize size = wxDisplay(this).GetClientArea().GetSize();
+        // Ensure display size is valid
+        if (size.y <= 0) size.y = 600;
         if (height > size.y)
             height = size.y;
         wxPoint pos = _requestPos;
         if (pos.y + height > size.y)
-            pos.y = size.y - height;
+            pos.y = std::max(0, size.y - height);
+        // Ensure height is valid
+        if (height <= 0) height = 100;
         this->SetSize({ 400, (int)height });
         this->SetPosition(pos);
     }
diff --git a/src/slic3r/GUI/Widgets/DropDown.cpp b/src/slic3r/GUI/Widgets/DropDown.cpp
index 380d23bff4..6ec0265564 100644
--- a/src/slic3r/GUI/Widgets/DropDown.cpp
+++ b/src/slic3r/GUI/Widgets/DropDown.cpp
@@ -365,15 +365,15 @@ void DropDown::messureSize()
     }
     szContent.y *= std::min((size_t)15, texts.size());
     szContent.y += texts.size() > 15 ? rowSize.y / 2 : 0;
-#ifdef __WXGTK__
-    // GTK requires width >= -1 and height > 0 for gtk_window_resize/set_size_request
-    if (szContent.x < 1) szContent.x = 1;
-    if (szContent.y < 1) szContent.y = 1;
-#endif
     wxWindow::SetSize(szContent);
 #ifdef __WXGTK__
     // Gtk has a wrapper window for popup widget
-    gtk_window_resize (GTK_WINDOW (m_widget), szContent.x, szContent.y);
+    // Fix for GNOME Platform 48 X11 backend: ensure size is valid before calling gtk_window_resize
+    int gtk_width = szContent.x;
+    int gtk_height = szContent.y;
+    if (gtk_width <= 0) gtk_width = 100;
+    if (gtk_height <= 0) gtk_height = 100;
+    gtk_window_resize(GTK_WINDOW(m_widget), gtk_width, gtk_height);
 #endif
     need_sync = false;
 }
diff --git a/src/slic3r/GUI/Widgets/DropDown.hpp b/src/slic3r/GUI/Widgets/DropDown.hpp
index e3cf9b4531..24507cb776 100644
--- a/src/slic3r/GUI/Widgets/DropDown.hpp
+++ b/src/slic3r/GUI/Widgets/DropDown.hpp
@@ -30,7 +30,7 @@ class DropDown : public PopupWindow
 
     wxSize textSize;
     wxSize iconSize;
-    wxSize rowSize;
+    wxSize rowSize{100, 30};  // Initialize with default values
 
     StateHandler state_handler;
     StateColor   text_color;