bugfix: make a fresh copy of Geom before transforming

frontend/ui/reader/readerview.lua

@@ -237,7 +237,7 @@ end
 function ReaderView:getScrollPageRect(page, rect_p)
 	local rect_s = Geom:new{}
 	for _, state in ipairs(self.page_states) do
-		local trans_p = Geom:new(rect_p)
+		local trans_p = Geom:new(rect_p):copy()
 		trans_p:transformByScale(state.zoom, state.zoom)
 		if page == state.page and state.visible_area:contains(trans_p) then
 			rect_s.x = rect_s.x + state.offset.x + trans_p.x - state.visible_area.x
@@ -287,7 +287,7 @@ end
 
 function ReaderView:getSinglePageRect(rect_p)
 	local rect_s = Geom:new{}
-	local trans_p = Geom:new(rect_p)
+	local trans_p = Geom:new(rect_p):copy()
 	trans_p:transformByScale(self.state.zoom, self.state.zoom)
 	if self.visible_area:contains(trans_p) then
 		rect_s.x = self.state.offset.x + trans_p.x - self.visible_area.x