Update readme

See https://community.ugfx.io/topic/4782-the-screen-is-redrawn-more-than-once/#comment-13706

Thanks to Sergey Kushnir.

changelog.txt

@@ -34,6 +34,7 @@ FEATURE:    LGDP4532 driver improvements.
 FIX:        Win32 Keyboard driver now retrieves lock key states on window activate
 FEATURE:    Add SSD1312 GDISP driver
 FEATURE:    Add CH1115 GDISP driver
+FIX:		Fix multiple redraws of GWIN windows (thanks to Sergey Kushnir)
 
 
 *** Release 2.9 ***

readme.txt

@@ -1,5 +1,4 @@
-Homepage:           http://ugfx.io
-Documentation:      http://wiki.ugfx.io
-API-Reference:      http://api.ugfx.io
-Forum:              http://community.ugfx.io
-uGFX-Studio:        http://studio.ugfx.io
+Homepage:           https://ugfx.io
+Documentation:      https://wiki.ugfx.io
+API-Reference:      https://api.ugfx.io
+Forum:              https://community.ugfx.io

src/gwin/gwin_wm.c

@@ -749,6 +749,7 @@ static void WM_Delete(GHandle gh) {
 
 static void WM_Redraw(GHandle gh) {
 	gU32	flags;
+    gU32    parents = 0;    // Used to indicate whether the window (gh) has parent(s).
 	
 	flags = gh->flags;
 	gh->flags &= ~(GWIN_FLG_NEEDREDRAW|GWIN_FLG_BGREDRAW|GWIN_FLG_PARENTREVEAL);
@@ -790,6 +791,8 @@ static void WM_Redraw(GHandle gh) {
 				if (gh->parent) {
 					// Child redraw is done
 
+                    parents++;
+
 					// Get the parent to redraw the area
 					gh = gh->parent;
 
@@ -806,6 +809,11 @@ static void WM_Redraw(GHandle gh) {
 			// Clear the area to the background color
 			gdispGFillArea(gh->display, gh->x, gh->y, gh->width, gh->height, gwinGetDefaultBgColor());
 
+            #if GWIN_NEED_CONTAINERS
+                if (!parents)
+                    return;
+            #endif
+
 			// Now loop over all windows looking for overlaps. Redraw them if they overlap the newly exposed area.
 			for(gx = gwinGetNextWindow(0); gx; gx = gwinGetNextWindow(gx)) {
 				if ((gx->flags & GWIN_FLG_SYSVISIBLE)