Make scrolling-by-selection smoother

This trivial patch makes scrolling-by-selection smoother by dividing
the step size and the time between steps by 8 when generating
synthetic events in work area.

The scrolling speed is unchanged, but the result is visually better.

(cherry picked from commit 1cc1f0ba27)

src/frontends/qt/GuiWorkArea.cpp

@@ -945,6 +945,8 @@ void GuiWorkArea::generateSyntheticMouseEvent()
 				step = 80000 / (time * time);
 				time = 40;
 			}
+			step /= 8;
+			time /= 8;
 		}
 		d->synthetic_mouse_event_.timeout.setTimeout(time);
 		d->synthetic_mouse_event_.timeout.start();

status.24x

@@ -33,6 +33,8 @@ What's new
 
 - Show font info in status line again.
 
+- Make scrolling smoother when using selection.
+
 
 * DOCUMENTATION AND LOCALIZATION