UI Bug fixes and code cleanup for Publish 3MF Dialog (#15690)

# Description
- Fixes an issue on macOS where the modified indicator can be cut-off.
- Remove unused code

src/slic3r/GUI/PublishSettingsDialog.cpp

@@ -1037,9 +1037,6 @@ size_t PublishSettingsDialog::section_group_for(Section kind)
         section.mixed_tabs = new TabCtrl(section.page, wxID_ANY, wxDefaultPosition, wxDefaultSize, s_tab_style);
         section.mixed_tabs->SetFont(Label::Body_14);
         section.mixed_tabs->SetBackgroundColour(GetBackgroundColour());
-        // The mixed tabs carry full swatch compositions: give them a touch more room than the
-        // filament tabs so neighbouring compositions stay distinguishable (must precede AppendItem).
-        section.mixed_tabs->SetItemSpace(FromDIP(3));
         page_sizer->Add(section.mixed_tabs, 0, wxEXPAND | wxTOP, FromDIP(2));
         section.mixed_tabs->Hide();
     }

src/slic3r/GUI/Widgets/Button.cpp

@@ -311,8 +311,11 @@ void Button::render(wxDC& dc)
         }
     }
     auto szContent = textSize;
+    // Whether the measured content reserved the text/icon gap. macOS measures an empty label
+    // as 0-high, so the gap is skipped there; the dot must not advance past it in that case.
+    const bool gap_reserved = szContent.y > 0;
     if (icon.bmp().IsOk()) {
-        if (szContent.y > 0) {
+        if (gap_reserved) {
             //BBS norrow size between text and icon
             if (vertical)
                 szContent.y += spacing;
@@ -357,10 +360,10 @@ void Button::render(wxDC& dc)
         dc.DrawBitmap(icon.bmp(), pt);
         //BBS norrow size between text and icon
         if (vertical) {
-            pt.y += szIcon.y + spacing;
+            pt.y += szIcon.y + (gap_reserved ? spacing : 0);
             pt.x = rcContent.x;
         } else {
-            pt.x += szIcon.x + spacing;
+            pt.x += szIcon.x + (gap_reserved ? spacing : 0);
             pt.y = rcContent.y;
         }
     }

src/slic3r/GUI/Widgets/TabCtrl.cpp

@@ -99,7 +99,7 @@ int TabCtrl::AppendItem(const wxString& item, int image, int selImage, void* cli
     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, item_space);
+    sizer->Add(btn, 0, wxALIGN_CENTER_VERTICAL);
     sizer->AddStretchSpacer(1);
     relayout();
     return btns.size() - 1;
@@ -256,12 +256,12 @@ void TabCtrl::relayout()
     int item   = sel + 1;
     int first  = 0;
     for (int i = 0; i < item; ++i)
-        offset += btns[i]->GetMinSize().x + item_space * 2;
+        offset += btns[i]->GetMinSize().x;
     if (item < btns.size())
-        offset += btns[item]->GetMinSize().x + item_space * 2;
+        offset += btns[item]->GetMinSize().x;
     int width = GetSize().x;
     for (int i = 0; i < btns.size(); ++i) {
-        auto size = btns[i]->GetMinSize().x + item_space * 2;
+        auto size = btns[i]->GetMinSize().x;
         if (i < sel && offset > width) {
             sizer->Show(i * 2 + 1, false);
             sizer->Show(i * 2 + 2, false);
@@ -284,26 +284,17 @@ void TabCtrl::relayout()
     if (item >= btns.size())
         --item;
     // Keep spacing 2 ~ 10 TAB_BUTTON_SPACE
-    int b = GetSize().x - offset - 10 - (item + 1 - first) * item_space * 8;
+    int b = GetSize().x - offset - 10 - (item + 1 - first) * 16;
     sizer->GetItem(item * 2 + 2)->SetMinSize({b > 0 ? b : 0, 0});
     Layout();
 }
 
-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.
+    // Mirrors relayout(): a 10px leading spacer plus every button's min width.
     int width = 10;
     for (const Button* btn : btns)
-        width += btn->GetMinSize().x + item_space * 2;
+        width += btn->GetMinSize().x;
     return width;
 }
 

src/slic3r/GUI/Widgets/TabCtrl.hpp

@@ -14,7 +14,6 @@ class TabCtrl : public StaticBox
 
     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);
@@ -64,10 +63,6 @@ public:
     int GetNextVisible(int item) const;
     bool IsVisible(unsigned int item) 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: