FINE I'll do it myself

src/render/text/viewer.cpp

@@ -105,24 +105,40 @@ RealRect intersect(const RealRect& a, const RealRect& b) {
   RealPoint tl = piecewise_max(a.topLeft(),     b.topLeft());
   RealPoint br = piecewise_min(a.bottomRight(), b.bottomRight());
   return RealRect(tl, RealSize(br - tl));
-}
+}
 
 void TextViewer::drawSelection(RotatedDC& dc, const TextStyle& style, size_t sel_start, size_t sel_end) {
   if (sel_start == sel_end) return;
-  if (sel_end < sel_start) swap(sel_start, sel_end);
+  if (sel_end < sel_start) swap(sel_start, sel_end);
+#ifdef __WXMSW__
   dc.SetBrush(*wxWHITE_BRUSH);
   dc.SetPen(*wxWHITE_PEN);
-  dc.SetLogicalFunction(wxXOR);
+  dc.SetLogicalFunction(wxXOR);
+#endif
   RealRect prev_rect(0,0,0,0);
   FOR_EACH(l, lines) {
     RealRect rect = l.selectionRectangle(dc, sel_start, sel_end);
-    if (rect.height > 0) dc.DrawRectangle(rect);
+    if (rect.height > 0) {
+#ifdef __WXMSW__
+      dc.DrawRectangle(rect);
+#else
+      dc.DrawInvertRectangle(rect);
+#endif
+    }
     // compensate for overlap between lines
     RealRect overlap = intersect(rect, prev_rect);
-    if (overlap.height > 0 && overlap.width > 0) dc.DrawRectangle(overlap);
+    if (overlap.height > 0 && overlap.width > 0) {
+#ifdef __WXMSW__
+      dc.DrawRectangle(overlap);
+#else
+      dc.DrawInvertRectangle(overlap);
+#endif
+    }
     prev_rect = rect;
-  }
+  }
-  dc.SetLogicalFunction(wxCOPY);
+#ifdef __WXMSW__
+  dc.SetLogicalFunction(wxCOPY);
+#endif
 }
 
 RealRect TextViewer::Line::selectionRectangle(const Rotation& rot, size_t sel_start, size_t sel_end) {

src/util/rotation.cpp

@@ -9,7 +9,8 @@
 #include <util/prec.hpp>
 #include <util/rotation.hpp>
 #include <gfx/gfx.hpp>
-#include <data/font.hpp>
+#include <data/font.hpp>
+#include <wx/rawbmp.h>
 
 // ----------------------------------------------------------------------------- : Rotation
 
@@ -276,6 +277,33 @@ void RotatedDC::DrawRoundedRectangle(const RealRect& r, double radius) {
   }
 }
 
+void RotatedDC::DrawInvertRectangle(const RealRect& r) {
+  wxRect r_ext = trRectToBB(r);
+
+  wxBitmap bmp(r_ext.width, r_ext.height, 24); 
+  wxMemoryDC memDC(bmp);
+  memDC.Blit(0, 0, r_ext.width, r_ext.height, &dc, r_ext.x, r_ext.y);
+  memDC.SelectObject(wxNullBitmap);
+
+  wxNativePixelData data(bmp);
+  if (!data) return; // Raw access not available on this platform/bitmap
+  wxNativePixelData::Iterator p(data);
+  for (int j = 0; j < r_ext.height; ++j) {
+    wxNativePixelData::Iterator rowStart = p;
+    for (int i = 0; i < r_ext.width; ++i) {
+      // Invert each channel
+      p.Red()   = 255 - p.Red();
+      p.Green() = 255 - p.Green();
+      p.Blue()  = 255 - p.Blue();
+      ++p; // Move to next pixel in the row
+    }
+    p = rowStart;
+    p.OffsetY(data, 1); // Move to the next row
+  }
+
+  dc.DrawBitmap(bmp, RealPoint(r_ext.x, r_ext.y));
+}
+
 void RotatedDC::DrawCircle(const RealPoint& center, double radius) {
   wxPoint p = tr(center);
   dc.DrawCircle(p.x + 1, p.y + 1, int(trS(radius)));

src/util/rotation.hpp

@@ -173,6 +173,7 @@ public:
   void DrawLine  (const RealPoint& p1,  const RealPoint& p2);
   void DrawRectangle(const RealRect& r);
   void DrawRoundedRectangle(const RealRect& r, double radius);
+  void DrawInvertRectangle(const RealRect& r);
   void DrawCircle(const RealPoint& center, double radius);
   void DrawEllipse(const RealPoint& center, const RealSize& size);
   /// Draw an arc of an ellipse, angles are in radians