Publish 3MF: support mixed filaments and per-extruder slot selection

- Publish mixed-filament slots as whole units: serialize the filament_mixed_* definition into project_config on import, grow the receiver's parallel arrays in lockstep, and report unappliable definitions as skipped instead of dropping them silently

- Per-extruder printer selection: one inner tab per extruder, rows keyed by full "#N" ids; single-extruder receivers collapse variants onto their slot (first applied, rest skipped), multi-extruder receivers override element-wise

- New per-slot "Enable" toggle gating what gets published; enabling a mix auto-enables + Full Publishes its components

- Mixed page previews: fixed-size ratio bar, ternary triangle (3 components) and Material Ratio vs Model Height graph (gradients), always visible regardless of Enable

- Tab strip shows full swatch compositions with adjustable spacing; barycentric helpers shared via FilamentBitmapUtils

src/slic3r/GUI/FilamentBitmapUtils.cpp

@@ -11,6 +11,45 @@
 
 namespace Slic3r { namespace GUI {
 
+// Barycentric utilities for a ternary (triangle) ratio picker.
+double tri_signed_area2(TriPoint a, TriPoint b, TriPoint c)
+{
+    return (b.x - a.x) * (c.y - a.y) - (c.x - a.x) * (b.y - a.y);
+}
+
+bool tri_contains(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2)
+{
+    double total = tri_signed_area2(v0, v1, v2);
+    if (std::abs(total) < 1e-9) return false;
+    double s0 = tri_signed_area2(p, v1, v2) / total;
+    double s1 = tri_signed_area2(v0, p, v2) / total;
+    double s2 = 1.0 - s0 - s1;
+    return s0 >= -0.001 && s1 >= -0.001 && s2 >= -0.001;
+}
+
+void tri_barycentric(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2,
+                     double& w0, double& w1, double& w2)
+{
+    double total = std::abs(tri_signed_area2(v0, v1, v2));
+    if (total < 1e-9) { w0 = w1 = w2 = 1.0 / 3.0; return; }
+    w0 = std::abs(tri_signed_area2(p, v1, v2)) / total;
+    w1 = std::abs(tri_signed_area2(v0, p, v2)) / total;
+    w2 = 1.0 - w0 - w1;
+    w0 = std::clamp(w0, 0.0, 1.0);
+    w1 = std::clamp(w1, 0.0, 1.0);
+    w2 = std::clamp(w2, 0.0, 1.0);
+    double s = w0 + w1 + w2;
+    if (s > 0) { w0 /= s; w1 /= s; w2 /= s; }
+}
+
+TriPoint tri_clamp(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2)
+{
+    double w0, w1, w2;
+    tri_barycentric(p, v0, v1, v2, w0, w1, w2);
+    return {w0 * v0.x + w1 * v1.x + w2 * v2.x,
+            w0 * v0.y + w1 * v1.y + w2 * v2.y};
+}
+
 void fill_gradient_rect_east(wxDC& dc, const wxRect& rect, const wxColour& from, const wxColour& to)
 {
     if (rect.width <= 0 || rect.height <= 0) return;
@@ -73,7 +112,7 @@ std::vector<wxColour> sample_gradient_ramp(const wxColour& first,
 // Resolve the curve a gradient slot is sampled with, mirroring the slicer's fallback in
 // ToolOrdering: a custom curve wins, otherwise a straight line between gradient_range's
 // endpoints, otherwise the 0.10 -> 0.90 default.
-static Slic3r::GradientCurve mixed_gradient_curve(const Slic3r::DynamicPrintConfig& cfg, size_t slot)
+Slic3r::GradientCurve mixed_gradient_curve(const Slic3r::DynamicPrintConfig& cfg, size_t slot)
 {
     const auto* curve_opt = cfg.option<ConfigOptionStrings>("filament_mixed_gradient_curve");
     if (curve_opt && slot < curve_opt->values.size() && !curve_opt->values[slot].empty()) {

src/slic3r/GUI/FilamentBitmapUtils.hpp

@@ -13,6 +13,16 @@ namespace Slic3r { class DynamicPrintConfig; struct GradientCurve; }
 
 namespace Slic3r { namespace GUI {
 
+// Barycentric utilities for a ternary (triangle) ratio picker, shared by the mixed-filament
+// editor and the Publish dialog's read-only definition preview.
+struct TriPoint { double x, y; };
+
+double tri_signed_area2(TriPoint a, TriPoint b, TriPoint c);
+bool tri_contains(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2);
+void tri_barycentric(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2,
+                     double& w0, double& w1, double& w2);
+TriPoint tri_clamp(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2);
+
 // Fills a rect with a west->east linear gradient by drawing solid 1px columns.
 // Use instead of wxDC::GradientFillLinear, whose CoreGraphics (CGShading) backend
 // fails to render on some macOS builds; solid fills are unaffected.
@@ -51,6 +61,12 @@ std::vector<wxColour> sample_gradient_ramp(const wxColour& first,
 // destination's height in pixels.
 std::vector<wxColour> mixed_gradient_ramp(const Slic3r::DynamicPrintConfig& cfg, size_t slot, int steps);
 
+// Resolve the curve a gradient slot is sampled with: the custom curve wins when it has at
+// least two points, otherwise a straight line between gradient_range's endpoints, otherwise
+// the 0.10 -> 0.90 default. Mirrors the slicer's ToolOrdering fallback so every preview
+// agrees with what gets sliced. Always returns a two-point curve.
+Slic3r::GradientCurve mixed_gradient_curve(const Slic3r::DynamicPrintConfig& cfg, size_t slot);
+
 // Fill rect with a ramp, ramp.front() along the bottom edge.
 void fill_gradient_ramp_rect(wxDC& dc, const wxRect& rect, const std::vector<wxColour>& ramp);
 

src/slic3r/GUI/MixedFilamentDialog.cpp

@@ -919,52 +919,8 @@ wxBoxSizer* MixedFilamentDialog::create_ratio_slider()
 }
 
 // ---- Triangle (ternary) ratio picker ----
-
-// Barycentric coordinate utilities
-struct TriPoint { double x, y; };
-
-static double tri_signed_area2(TriPoint a, TriPoint b, TriPoint c)
-{
-    return (b.x - a.x) * (c.y - a.y) - (c.x - a.x) * (b.y - a.y);
-}
-
-static bool tri_contains(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2)
-{
-    double total = tri_signed_area2(v0, v1, v2);
-    if (std::abs(total) < 1e-9) return false;
-    double s0 = tri_signed_area2(p, v1, v2) / total;
-    double s1 = tri_signed_area2(v0, p, v2) / total;
-    double s2 = 1.0 - s0 - s1;
-    return s0 >= -0.001 && s1 >= -0.001 && s2 >= -0.001;
-}
-
-static void tri_barycentric(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2,
-                            double& w0, double& w1, double& w2)
-{
-    double total = std::abs(tri_signed_area2(v0, v1, v2));
-    if (total < 1e-9) { w0 = w1 = w2 = 1.0 / 3.0; return; }
-    w0 = std::abs(tri_signed_area2(p, v1, v2)) / total;
-    w1 = std::abs(tri_signed_area2(v0, p, v2)) / total;
-    w2 = 1.0 - w0 - w1;
-    w0 = std::clamp(w0, 0.0, 1.0);
-    w1 = std::clamp(w1, 0.0, 1.0);
-    w2 = std::clamp(w2, 0.0, 1.0);
-    double s = w0 + w1 + w2;
-    if (s > 0) { w0 /= s; w1 /= s; w2 /= s; }
-}
-
-static TriPoint tri_clamp(TriPoint p, TriPoint v0, TriPoint v1, TriPoint v2)
-{
-    double w0, w1, w2;
-    tri_barycentric(p, v0, v1, v2, w0, w1, w2);
-    w0 = std::clamp(w0, 0.0, 1.0);
-    w1 = std::clamp(w1, 0.0, 1.0);
-    w2 = std::clamp(w2, 0.0, 1.0);
-    double s = w0 + w1 + w2;
-    if (s > 0) { w0 /= s; w1 /= s; w2 /= s; }
-    return {w0 * v0.x + w1 * v1.x + w2 * v2.x,
-            w0 * v0.y + w1 * v1.y + w2 * v2.y};
-}
+// The barycentric utilities (TriPoint, tri_contains, tri_barycentric, tri_clamp) live in
+// FilamentBitmapUtils so the Publish dialog can mirror this picker read-only.
 
 wxBoxSizer* MixedFilamentDialog::create_triangle_picker()
 {

src/slic3r/GUI/PublishSettingsDialog.hpp

@@ -7,8 +7,10 @@
 #include "libslic3r/PublishSettings.hpp"
 
 #include <wx/wx.h>
+#include <wx/colour.h>
 #include <wx/scrolwin.h>
 #include <wx/menu.h>
+#include <utility>
 #include <vector>
 #include <string>
 
@@ -105,9 +107,18 @@ private:
         wxPoint scroll_pos{0, 0};
         wxStaticBitmap* filament_color_chip{nullptr};
         wxStaticText* title_label{nullptr}; // material title (static text; Full Publish carries the label elsewhere)
+        // "Enable": while unchecked nothing of this slot is exported and everything below the
+        // header row is hidden. For physical slots the Full Publish toggle sits on a second
+        // line (full_line_item) visible only when enabled; for mixed slots Enable alone implies
+        // publishing the mix definition, so no Full Publish widget exists at all.
+        wxCheckBox* enable_check{nullptr};
+        wxSizerItem* full_line_item{nullptr}; // sizer item of the Full Publish line (physical slots only)
         // "Full Publish": while checked, the whole slot preset is serialized and its rows
         // (incl. Color/Type) are disabled.
         wxCheckBox* full_check{nullptr};
+        // True for a mixed-color filament slot: no Material/Retraction rows; Enable publishes
+        // the slot's gradient/ratio definition as a whole.
+        bool is_mixed{false};
         // Material identity, only for Section::Material categories.
         std::string filament_type;
         std::string filament_vendor;
@@ -118,6 +129,21 @@ private:
         std::vector<size_t> rows; // flattened rows of this category
     };
 
+    // Frozen snapshot of a mixed filament slot's definition for the read-only visualization
+    // painted on the slot's page. Plain data only: the paint handler must never touch the
+    // config. For gradient slots the curve is pre-sampled (t, ratio) pairs, where ratio is the
+    // first component's share over model height; anchors carry the raw control points.
+    struct MixedVisualSpec
+    {
+        bool valid{false};
+        bool is_gradient{false};
+        std::vector<wxColour> component_colours;   // colour per component, in config order
+        std::vector<double> ratios;                // sublayer shares summing to ~1 (non-gradient)
+        std::vector<double> tri_weights;           // 3-component mixes: barycentric shares
+        std::vector<std::pair<double, double>> gradient_samples;
+        std::vector<std::pair<double, double>> gradient_anchors;
+    };
+
     // One outer TabCtrl page. Category entries are its inner tabs.
     struct SectionGroup
     {
@@ -127,13 +153,24 @@ private:
         ScalableBitmap icon_bmp;      // tab icon next to the title; rescaled on DPI change
         wxPanel* page{nullptr};
         TabCtrl* tabs{nullptr};
+        // Second tab strip, below the main one, listing only the mixed-color filament slots.
+        // Present on the Material section only (null elsewhere).
+        TabCtrl* mixed_tabs{nullptr};
         wxPanel* page_host{nullptr};
         wxBoxSizer* page_host_sizer{nullptr};
         int selected_inner{-1};
-        std::vector<size_t> categories; // indices into m_categories
+        // Selected mixed tab (index into mixed_categories), valid while a mixed slot page is shown.
+        int selected_mixed{-1};
+        std::vector<size_t> categories;      // indices into m_categories (physical slots)
+        std::vector<size_t> mixed_categories; // indices into m_categories (mixed slots)
     };
 
     void build_option_model();
+    // Frozen snapshot of a mixed slot's definition for the page visualization, resolved from
+    // the full config once at dialog-build time. Gradient slots pre-sample exactly what the
+    // slicer will print: the custom curve wins over the gradient_range endpoints over the
+    // 0.10 -> 0.90 default (the resolution FilamentBitmapUtils::mixed_gradient_curve mirrors).
+    static MixedVisualSpec make_mixed_visual_spec(const Slic3r::DynamicPrintConfig& full, size_t slot);
     void apply_filter(const wxString& filter_text);
     // Menu-only pseudo filters: show only the checked ("Filter selected") or only the
     // unchecked ("Filter non-selected") rows. The search box keeps the user's text.
@@ -147,13 +184,21 @@ private:
     void set_row_bold(Row& row, bool bold);
     // "Full Publish" toggled: disables/enables the material's rows.
     void on_full_toggle(size_t category_index);
+    // "Enable" toggled on a material slot: reveals/hides everything below the header and, for a
+    // mixed slot, auto-selects its component filaments' "Enable" + "Full Publish" toggles.
+    void on_enable_toggle(size_t category_index);
+    // Read-only visualization of a mixed slot's definition (a stacked ratio bar, or the
+    // Material Ratio vs Model Height graph for a gradient), inserted above the info hint
+    // inside the category's scroll area.
+    void add_mixed_visual(size_t category_index, const MixedVisualSpec& spec);
     // Return/create the fixed outer page for a Section kind.
     size_t section_group_for(Section kind);
     size_t category_index_for(const wxString& title,
                               Section section,
                               size_t group,
                               size_t source_index,
-                              const PublishMaterialIdentity& identity = PublishMaterialIdentity());
+                              const PublishMaterialIdentity& identity = PublishMaterialIdentity(),
+                              bool is_mixed                          = false);
     size_t subcategory_index_for(size_t category_index, const wxString& title, const wxString& icon);
     void add_row_ui(const std::string& key,
                     const wxString& label,
@@ -167,8 +212,10 @@ private:
     void save_scroll_position(Category& category);
     void show_outer_page(size_t section_index);
     void show_inner_page(size_t section_index, int inner_index);
+    void show_mixed_page(size_t section_index, int mixed_index);
     void on_outer_tab_changed(wxCommandEvent& event);
     void on_inner_tab_changed(size_t section_index, wxCommandEvent& event);
+    void on_mixed_tab_changed(size_t section_index, wxCommandEvent& event);
     bool row_is_visible(const Row& row) const;
     void apply_visibility();
     void bind_tab_events();
@@ -190,6 +237,7 @@ private:
     wxString m_info_nonsel;
     wxString m_info_allsel;
     wxString m_info_empty;
+    wxString m_info_mix; // body hint shown for a mixed slot (published as a whole)
 
     ScalableBitmap m_search;
     ScalableBitmap m_menu;

src/slic3r/GUI/Widgets/TabCtrl.cpp

@@ -2,8 +2,8 @@
 
 #include <wx/dc.h>
 
-wxDEFINE_EVENT( wxEVT_TAB_SEL_CHANGING, wxCommandEvent );
-wxDEFINE_EVENT( wxEVT_TAB_SEL_CHANGED, wxCommandEvent );
+wxDEFINE_EVENT(wxEVT_TAB_SEL_CHANGING, wxCommandEvent);
+wxDEFINE_EVENT(wxEVT_TAB_SEL_CHANGED, wxCommandEvent);
 
 BEGIN_EVENT_TABLE(TabCtrl, StaticBox)
 
@@ -22,11 +22,7 @@ END_EVENT_TABLE()
 #define TAB_BUTTON_PADDING_Y 2
 #define TAB_BUTTON_PADDING TAB_BUTTON_PADDING_X, TAB_BUTTON_PADDING_Y
 
-TabCtrl::TabCtrl(wxWindow *      parent,
-                   wxWindowID      id,
-                   const wxPoint & pos,
-                   const wxSize &  size,
-                   long            style)
+TabCtrl::TabCtrl(wxWindow* parent, wxWindowID id, const wxPoint& pos, const wxSize& size, long style)
     : StaticBox(parent, id, pos, size, style)
 {
 #if 0
@@ -42,14 +38,11 @@ TabCtrl::TabCtrl(wxWindow *      parent,
     hsizer->Add(sizer, 0, wxEXPAND | wxBOTTOM, border_width * 4);
     SetSizer(hsizer);
     Bind(wxEVT_COMMAND_BUTTON_CLICKED, &TabCtrl::buttonClicked, this);
-    //wxString reason;
-    //IsTransparentBackgroundSupported(&reason);
+    // wxString reason;
+    // IsTransparentBackgroundSupported(&reason);
 }
 
-TabCtrl::~TabCtrl()
-{
-    delete images;
-}
+TabCtrl::~TabCtrl() { delete images; }
 
 int TabCtrl::GetSelection() const { return sel; }
 
@@ -75,14 +68,11 @@ void TabCtrl::SelectItem(int item)
     Refresh();
 }
 
-void TabCtrl::Unselect()
-{
-    SelectItem(-1);
-}
+void TabCtrl::Unselect() { SelectItem(-1); }
 
 void TabCtrl::Rescale()
 {
-    for (auto & b : btns)
+    for (auto& b : btns)
         b->Rescale();
     relayout();
 }
@@ -96,23 +86,20 @@ bool TabCtrl::SetFont(wxFont const& font)
     return true;
 }
 
-int TabCtrl::AppendItem(const wxString &item,
-                     int image, int selImage,
-                     void * clientData)
+int TabCtrl::AppendItem(const wxString& item, int image, int selImage, void* clientData)
 {
-    Button * btn = new Button();
+    Button* btn = new Button();
     btn->Create(this, item, "", wxBORDER_NONE);
     btn->SetFont(GetFont());
-    btn->SetTextColor(StateColor(
-        std::make_pair(0x6B6B6C, (int) StateColor::NotChecked),
-        std::make_pair(*wxLIGHT_GREY, (int) StateColor::Normal)));
+    btn->SetTextColor(
+        StateColor(std::make_pair(0x6B6B6C, (int) StateColor::NotChecked), std::make_pair(*wxLIGHT_GREY, (int) StateColor::Normal)));
     btn->SetBackgroundColor(StateColor());
     btn->SetCornerRadius(0);
     btn->SetPaddingSize({TAB_BUTTON_PADDING});
     btns.push_back(btn);
     if (btns.size() > 1)
         sizer->GetItem(sizer->GetItemCount() - 1)->SetMinSize({0, 0});
-    sizer->Add(btn, 0, wxALIGN_CENTER_VERTICAL | wxLEFT | wxRIGHT, TAB_BUTTON_SPACE * 2);
+    sizer->Add(btn, 0, wxALIGN_CENTER_VERTICAL | wxLEFT | wxRIGHT, item_space * 2);
     sizer->AddStretchSpacer(1);
     relayout();
     return btns.size() - 1;
@@ -144,7 +131,7 @@ bool TabCtrl::DeleteItem(int item)
         sizer->GetItem(sizer->GetItemCount() - 1)->SetMinSize({0, 0});
 
     if (selection_changed) {
-        sel--;  // `relayout()` uses `sel` so we need to update this before calling `relayout()`
+        sel--; // `relayout()` uses `sel` so we need to update this before calling `relayout()`
     }
     relayout();
     if (selection_changed) {
@@ -167,14 +154,12 @@ void TabCtrl::DeleteAllItems()
 
 unsigned int TabCtrl::GetCount() const { return btns.size(); }
 
-wxString TabCtrl::GetItemText(unsigned int item) const
-{
-    return item < btns.size() ? btns[item]->GetLabel() : wxString{};
-}
+wxString TabCtrl::GetItemText(unsigned int item) const { return item < btns.size() ? btns[item]->GetLabel() : wxString{}; }
 
-void TabCtrl::SetItemText(unsigned int item, wxString const &value)
+void TabCtrl::SetItemText(unsigned int item, wxString const& value)
 {
-    if (item >= btns.size()) return;
+    if (item >= btns.size())
+        return;
     btns[item]->SetLabel(value);
 }
 
@@ -188,61 +173,59 @@ void TabCtrl::SetItemBitmap(unsigned int item, const wxBitmap& bitmap)
 
 bool TabCtrl::GetItemBold(unsigned int item) const
 {
-    if (item >= btns.size()) return false;
+    if (item >= btns.size())
+        return false;
     return btns[item]->GetFont() == bold;
 }
 
 void TabCtrl::SetItemBold(unsigned int item, bool bold)
 {
-    if (item >= btns.size()) return;
+    if (item >= btns.size())
+        return;
     btns[item]->SetFont(bold ? this->bold : GetFont());
     btns[item]->Rescale();
 }
 
 void* TabCtrl::GetItemData(unsigned int item) const
 {
-    if (item >= btns.size()) return nullptr;
+    if (item >= btns.size())
+        return nullptr;
     return btns[item]->GetClientData();
 }
 
 void TabCtrl::SetItemData(unsigned int item, void* clientData)
 {
-    if (item >= btns.size()) return;
+    if (item >= btns.size())
+        return;
     btns[item]->SetClientData(clientData);
 }
 
 void TabCtrl::AssignImageList(wxImageList* imageList)
 {
-    if (images == imageList) return;
+    if (images == imageList)
+        return;
     delete images;
     images = imageList;
 }
 
-void TabCtrl::SetItemTextColour(unsigned int item, const StateColor &col)
+void TabCtrl::SetItemTextColour(unsigned int item, const StateColor& col)
 {
-    if (item >= btns.size()) return;
+    if (item >= btns.size())
+        return;
     btns[item]->SetTextColor(col);
 }
 
-int TabCtrl::GetFirstVisibleItem() const
-{
-    return btns.size() == 0 ? -1 : 0;
-}
+int TabCtrl::GetFirstVisibleItem() const { return btns.size() == 0 ? -1 : 0; }
 
-int TabCtrl::GetNextVisible(int item) const
-{
-    return ++item < btns.size() ? item : -1;
-}
+int TabCtrl::GetNextVisible(int item) const { return ++item < btns.size() ? item : -1; }
 
-bool TabCtrl::IsVisible(unsigned int item) const
-{
-    return true;
-}
+bool TabCtrl::IsVisible(unsigned int item) const { return true; }
 
 void TabCtrl::DoSetSize(int x, int y, int width, int height, int sizeFlags)
 {
     wxWindow::DoSetSize(x, y, width, height, sizeFlags);
-    if (sizeFlags & wxSIZE_USE_EXISTING) return;
+    if (sizeFlags & wxSIZE_USE_EXISTING)
+        return;
     relayout();
 }
 
@@ -250,7 +233,9 @@ void TabCtrl::DoSetSize(int x, int y, int width, int height, int sizeFlags)
 
 WXLRESULT TabCtrl::MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
 {
-    if (nMsg == WM_GETDLGCODE) { return DLGC_WANTARROWS; }
+    if (nMsg == WM_GETDLGCODE) {
+        return DLGC_WANTARROWS;
+    }
     return wxWindow::MSWWindowProc(nMsg, wParam, lParam);
 }
 
@@ -259,15 +244,15 @@ WXLRESULT TabCtrl::MSWWindowProc(WXUINT nMsg, WXWPARAM wParam, WXLPARAM lParam)
 void TabCtrl::relayout()
 {
     int offset = 10;
-    int item = sel + 1;
-    int first = 0;
+    int item   = sel + 1;
+    int first  = 0;
     for (int i = 0; i < item; ++i)
-        offset += btns[i]->GetMinSize().x + TAB_BUTTON_SPACE * 2;
+        offset += btns[i]->GetMinSize().x + item_space * 2;
     if (item < btns.size())
-        offset += btns[item]->GetMinSize().x + TAB_BUTTON_SPACE * 2;
-    int  width = GetSize().x;
+        offset += btns[item]->GetMinSize().x + item_space * 2;
+    int width = GetSize().x;
     for (int i = 0; i < btns.size(); ++i) {
-        auto size = btns[i]->GetMinSize().x + TAB_BUTTON_SPACE * 2;
+        auto size = btns[i]->GetMinSize().x + item_space * 2;
         if (i < sel && offset > width) {
             sizer->Show(i * 2 + 1, false);
             sizer->Show(i * 2 + 2, false);
@@ -288,23 +273,32 @@ void TabCtrl::relayout()
         sizer->GetItem(i * 2 + 2)->SetMinSize({0, 0});
     }
     if (item >= btns.size())
-        -- item;
+        --item;
     // Keep spacing 2 ~ 10 TAB_BUTTON_SPACE
-    int b = GetSize().x - offset - 10 - (item + 1 - first) * TAB_BUTTON_SPACE * 8;
+    int b = GetSize().x - offset - 10 - (item + 1 - first) * item_space * 8;
     sizer->GetItem(item * 2 + 2)->SetMinSize({b > 0 ? b : 0, 0});
     Layout();
 }
 
-int TabCtrl::buttons_best_width() const
+void TabCtrl::SetItemSpace(int space)
+{
+    if (space < 0 || space == item_space)
+        return;
+    item_space = space;
+    relayout();
+    Refresh();
+}
+
+int TabCtrl::GetFullSize() const
 {
     // Mirrors relayout(): a 10px leading spacer plus every button's min width and spacing.
     int width = 10;
-    for (const Button *btn : btns)
-        width += btn->GetMinSize().x + TAB_BUTTON_SPACE * 2;
+    for (const Button* btn : btns)
+        width += btn->GetMinSize().x + item_space * 2;
     return width;
 }
 
-void TabCtrl::buttonClicked(wxCommandEvent &event)
+void TabCtrl::buttonClicked(wxCommandEvent& event)
 {
     SetFocus();
     auto btn  = event.GetEventObject();
@@ -312,7 +306,7 @@ void TabCtrl::buttonClicked(wxCommandEvent &event)
     SelectItem(iter == btns.end() ? -1 : iter - btns.begin());
 }
 
-void TabCtrl::keyDown(wxKeyEvent &event)
+void TabCtrl::keyDown(wxKeyEvent& event)
 {
     switch (event.GetKeyCode()) {
     case WXK_UP:
@@ -331,11 +325,13 @@ void TabCtrl::keyDown(wxKeyEvent &event)
 void TabCtrl::doRender(wxDC& dc)
 {
     wxSize size = GetSize();
-    int states = state_handler.states();
-    if (sel < 0) { return; }
+    int states  = state_handler.states();
+    if (sel < 0) {
+        return;
+    }
 
-    auto x1 = btns[sel]->GetPosition().x;
-    auto x2 = x1 + btns[sel]->GetSize().x;
+    auto x1       = btns[sel]->GetPosition().x;
+    auto x2       = x1 + btns[sel]->GetSize().x;
     const int BS2 = (1 + border_width) / 2;
 #if 0
     const int BS = border_width / 2;

src/slic3r/GUI/Widgets/TabCtrl.hpp

@@ -3,33 +3,30 @@
 
 #include "Button.hpp"
 
-wxDECLARE_EVENT( wxEVT_TAB_SEL_CHANGING, wxCommandEvent );
-wxDECLARE_EVENT( wxEVT_TAB_SEL_CHANGED, wxCommandEvent );
+wxDECLARE_EVENT(wxEVT_TAB_SEL_CHANGING, wxCommandEvent);
+wxDECLARE_EVENT(wxEVT_TAB_SEL_CHANGED, wxCommandEvent);
 
 class TabCtrl : public StaticBox
 {
     std::vector<Button*> btns;
     wxImageList* images = nullptr;
-    wxBoxSizer * sizer = nullptr;
+    wxBoxSizer* sizer   = nullptr;
 
     int sel = -1;
     wxFont bold;
+    int item_space = 2; // space around each button, both sides (SetItemSpace)
 
 public:
-    TabCtrl(wxWindow *      parent,
-             wxWindowID      id,
-             const wxPoint & pos       = wxDefaultPosition,
-             const wxSize &  size      = wxDefaultSize,
-             long            style     = 0);
+    TabCtrl(wxWindow* parent, wxWindowID id, const wxPoint& pos = wxDefaultPosition, const wxSize& size = wxDefaultSize, long style = 0);
 
     ~TabCtrl();
 
 public:
-    virtual bool SetFont(wxFont const & font) override;
+    virtual bool SetFont(wxFont const& font) override;
 
 public:
-    int AppendItem(const wxString &item, int image = -1, int selImage = -1, void *clientData = nullptr);
-    int AppendItem(const wxString &item, const wxBitmap& bitmap, void *clientData = nullptr);
+    int AppendItem(const wxString& item, int image = -1, int selImage = -1, void* clientData = nullptr);
+    int AppendItem(const wxString& item, const wxBitmap& bitmap, void* clientData = nullptr);
 
     bool DeleteItem(int item);
 
@@ -37,7 +34,7 @@ public:
 
     unsigned int GetCount() const;
 
-    int  GetSelection() const;
+    int GetSelection() const;
 
     void SelectItem(int item);
 
@@ -46,16 +43,16 @@ public:
     virtual void Rescale();
 
     wxString GetItemText(unsigned int item) const;
-    void     SetItemText(unsigned int item, wxString const &value);
-    void     SetItemBitmap(unsigned int item, const wxBitmap& bitmap);
+    void SetItemText(unsigned int item, wxString const& value);
+    void SetItemBitmap(unsigned int item, const wxBitmap& bitmap);
 
-    bool     GetItemBold(unsigned int item) const;
-    void     SetItemBold(unsigned int item, bool bold);
+    bool GetItemBold(unsigned int item) const;
+    void SetItemBold(unsigned int item, bool bold);
 
-    void*    GetItemData(unsigned int item) const;
-    void     SetItemData(unsigned int item, void *clientData);
-    
-    void AssignImageList(wxImageList *imageList);
+    void* GetItemData(unsigned int item) const;
+    void SetItemData(unsigned int item, void* clientData);
+
+    void AssignImageList(wxImageList* imageList);
 
     void SetItemTextColour(unsigned int item, const StateColor& col);
 
@@ -64,8 +61,11 @@ public:
     int GetNextVisible(int item) const;
     bool IsVisible(unsigned int item) const;
 
-    // Width of the tab strip that keeps every button visible (used to size the Publish dialog).
-    int buttons_best_width() const;
+    // Extra space around each tab button (in px on both sides). Defaults to the control-wide
+    // standard; call before appending items so every button picks it up.
+    void SetItemSpace(int space);
+
+    int GetFullSize() const;
 
 private:
     virtual void DoSetSize(int x, int y, int width, int height, int sizeFlags = wxSIZE_AUTO) override;
@@ -76,10 +76,10 @@ private:
 
     void relayout();
 
-    void buttonClicked(wxCommandEvent & event);
-    void keyDown(wxKeyEvent &event);
+    void buttonClicked(wxCommandEvent& event);
+    void keyDown(wxKeyEvent& event);
 
-    void doRender(wxDC & dc) override;
+    void doRender(wxDC& dc) override;
 
     // some useful events
     bool sendTabCtrlEvent(bool changing = false);