Avoid rounding issue when painting selection

This issue was already addressed in the all_sel case. It only happens
at specific zoom and jusification values.

Fixes part of #8883.

(cherry picked from commit 71563835c7)

src/RowPainter.cpp

@@ -687,8 +687,9 @@ void RowPainter::paintSelection() const
 			double x2 = e.pos2x(to);
 			if (x1 > x2)
 				swap(x1, x2);
-			pi_.pain.fillRectangle(int(x + x1), y1, int(x2 - x1), y2 - y1,
-			                       Color_selection);
+			// the 3rd argument is written like that to avoid rounding issues
+			pi_.pain.fillRectangle(int(x + x1), y1, int(x2 + x) - int(x1 + x),
+			                       y2 - y1, Color_selection);
 		}
 		x += e.full_width();
 	}

status.22x

@@ -69,6 +69,8 @@ What's new
 
 - Fix glacial performance with ancient Hebrew text on macOS.
 
+- Fix hole in selection for some zoom and justification values (bug 8883).
+
 - Fix potential crash when cursor enters an inset (bug 10691).