Remove borders and paddings from native controls on Linux (#14873)

* init

* update

* Update SpinInput.cpp

* possible fix for em_unit

* button alignment

* match titlebar height

* revert em_value for macOS and Windows

* Update GUI_Utils.hpp

* Merge branch 'main' into linux-black-borders-2

* Revert "button alignment"

This reverts commit 3fc7461071.

* Revert "match titlebar height"

This reverts commit c4aa1d9f1e.

* revert dpi changes

* match platform tags

* remove radio box borders

* Fix code indent

src/slic3r/GUI/Widgets/RadioBox.cpp

@@ -2,6 +2,10 @@
 
 #include "../wxExtensions.hpp"
 
+#ifdef __WXGTK__
+#include "../GUI_Utils.hpp"
+#endif
+
 namespace Slic3r {
 namespace GUI {
 RadioBox::RadioBox(wxWindow *parent)
@@ -15,6 +19,7 @@ RadioBox::RadioBox(wxWindow *parent)
     // Bind(wxEVT_TOGGLEBUTTON, [this](auto& e) { update(); e.Skip(); });
     update();
 #ifdef __WXGTK__
+    Slic3r::GUI::RemoveButtonBorder(this);
     wxSize bestSize = GetBestSize();
     bestSize.IncTo(m_on.GetBmpSize());
     SetSize(bestSize);