update

src/slic3r/GUI/GUI_Utils.cpp

@@ -589,6 +589,58 @@ void RemoveButtonBorder(wxWindow* win)
     );
 #endif
 }
+
+void RemoveInputBorder(wxWindow* win)
+{
+    GtkWidget* widget = win->GetHandle();
+    if (!widget) return;
+
+#if GTK_CHECK_VERSION(3, 0, 0)
+    // GTK3+: use CSS provider
+    GtkCssProvider* provider = gtk_css_provider_new();
+
+    // Target 'entry' and its inner subnodes (like text selection areas)
+    const char* css =
+        "entry, entry text, entry undershoot {"
+        "  border: none;"
+        "  outline: none;"
+        "  box-shadow: none;"
+        "  padding: 0px;"
+        "  margin: 0px;"
+        "  min-height: 0px;"
+        "  min-width: 0px;"
+        "  background: none;"
+        "}";
+
+#if GTK_CHECK_VERSION(4, 0, 0)
+    // GTK4
+    gtk_css_provider_load_from_data(provider, css, -1);
+#else
+    // GTK3
+    gtk_css_provider_load_from_data(provider, css, -1, nullptr);
+#endif
+
+    GtkStyleContext* ctx = gtk_widget_get_style_context(widget);
+    gtk_style_context_add_provider(
+        ctx,
+        GTK_STYLE_PROVIDER(provider),
+        GTK_STYLE_PROVIDER_PRIORITY_USER
+    );
+    g_object_unref(provider);
+
+#else
+    // GTK2: Target the x/y thickness of the entry widget
+    gtk_rc_parse_string(
+        "style \"no-padding-entry\" {"
+        "  xthickness = 0"
+        "  ythickness = 0"
+        "  GtkEntry::inner-border = { 0, 0, 0, 0 }"
+        "  GtkEntry::focus-line-width = 0"
+        "}"
+        "class \"GtkEntry\" style \"no-padding-entry\""
+    );
+#endif
+}
 #endif // __WXGTK__
 
 #ifdef __linux__

src/slic3r/GUI/GUI_Utils.hpp

@@ -467,6 +467,7 @@ void staticbox_remove_margin(wxStaticBox* sb);
 
 #ifdef __WXGTK3__
 void RemoveButtonBorder(wxWindow* win);
+void RemoveInputBorder(wxWindow* win);
 #endif
 
 #if defined(__WXOSX__) || defined(__linux__)

src/slic3r/GUI/Widgets/CheckBox.cpp

@@ -2,7 +2,7 @@
 
 #include "../wxExtensions.hpp"
 
-#ifdef __WXGTK3__
+#ifdef __WXGTK__
 #include "../GUI_Utils.hpp"
 #endif
 

src/slic3r/GUI/Widgets/SwitchButton.cpp

@@ -12,7 +12,7 @@
 #include "libslic3r/MacUtils.hpp"
 #endif
 
-#ifdef __WXGTK3__
+#ifdef __WXGTK__
 #include "../GUI_Utils.hpp"
 #endif
 

src/slic3r/GUI/Widgets/TextInput.cpp

@@ -6,6 +6,10 @@
 #include <wx/dcclient.h>
 #include <wx/dcgraph.h>
 
+#ifdef __WXGTK__
+#include "../GUI_Utils.hpp"
+#endif
+
 BEGIN_EVENT_TABLE(TextInput, StaticBox)
 
 EVT_PAINT(TextInput::paintEvent)
@@ -60,6 +64,11 @@ void TextInput::Create(wxWindow *     parent,
     state_handler.attach({&label_color, & text_color});
     state_handler.update_binds();
     text_ctrl = new TextCtrl(this, wxID_ANY, text, {4, 4}, wxDefaultSize, style | wxBORDER_NONE | wxTE_PROCESS_ENTER);
+
+#ifdef __WXGTK__
+    Slic3r::GUI::RemoveInputBorder(text_ctrl);
+#endif
+
     text_ctrl->SetFont(Label::Body_14);
     text_ctrl->SetInitialSize(text_ctrl->GetBestSize());
     text_ctrl->SetBackgroundColour(background_color.colorForStates(state_handler.states()));