LCL: made IsEmptyRect winapi compatible, Rect(0,0,0,0) is just an example of an empty rect (bug #9495)

git-svn-id: trunk@11859 -

docs/xml/lcl/lclintf.xml

@@ -3649,8 +3649,12 @@
       </element>
       <!-- function Visibility: default -->
       <element name="IsRectEmpty">
-        <short/>
+        <short>Returns true, if the rectangle is empty</short>
-        <descr/>
+        <descr>IsEmptyRect returns true, if the area of the rectangle described by ARect is empty,
+  i.e. right coordinate is less than or equal to the left coordinate,
+ or the bottom coordinate is less than or equal to the top coordinate
+
+</descr>
         <errors/>
         <seealso/>
       </element>

lcl/include/winapi.inc

@@ -1152,12 +1152,14 @@ end;
   Params: const lprc: TRect
   Returns: Boolean
 
-  Returns true if ARect is (0,0,0,0)
+  Returns true if ARect is the area of the rectangle is empty,
+  i.e. right coordinate is less than or equal to the left coordinate,
+  or the bottom coordinate is less than or equal to the top coordinate
  ------------------------------------------------------------------------------}
 function IsRectEmpty(const ARect: TRect): Boolean;
 begin
   with ARect do
-    Result := (Left = 0) and (Top = 0) and (Right = 0) and (Bottom = 0);
+    Result := (Right <= Left) or (Bottom <= Top);
 end;
 
 {------------------------------------------------------------------------------