Index: /CKEditor/branches/prototype/_source/plugins/flash/dialogs/flash.js
===================================================================
--- /CKEditor/branches/prototype/_source/plugins/flash/dialogs/flash.js	(revision 2835)
+++ /CKEditor/branches/prototype/_source/plugins/flash/dialogs/flash.js	(revision 2836)
@@ -400,4 +400,5 @@
 										return true;
 									}
+									alert( editor.lang.common.validateNumberFailed );
 									return false;
 								}
@@ -419,4 +420,5 @@
 										return true;
 									}
+									alert( editor.lang.common.validateNumberFailed );
 									return false;
 								}
Index: /CKEditor/branches/prototype/_source/plugins/image/dialogs/image.js
===================================================================
--- /CKEditor/branches/prototype/_source/plugins/image/dialogs/image.js	(revision 2835)
+++ /CKEditor/branches/prototype/_source/plugins/image/dialogs/image.js	(revision 2836)
@@ -26,4 +26,5 @@
 	var uploadAction = 'nowhere.php';
 	var regexSize = /^\s*(\d+)((px)|\%)?\s*$/i;
+	var regexValidSize = /^(\d+)\%?$|^$/i;
 	var imageDialog = ( dialogType == 'image' );
 	var previewAreaHtml = '<div>' + CKEDITOR.tools.htmlEncode( editor.lang.image.preview ) +'<br>'+
@@ -778,11 +779,12 @@
 														validate: function()
 														{
-															// TODO Check content -  integer or percent.
-															//var func = CKEDITOR.dialog.validate.integer( editor.lang.common.validateNumberFailed );
-															//var isValid = func.apply( this );
-															isValid = true;
-															if ( isValid )
+															var aMatch  =  this.getValue().match( regexValidSize );
+															if ( aMatch )
+															{
 																addChange( 'width', this, 'image' );
-															return isValid;
+																return true;
+															}
+															alert( editor.lang.common.validateNumberFailed );
+															return false;
 														}
 													},
@@ -798,11 +800,12 @@
 														validate: function()
 														{
-															// TODO Check content -  integer or percent.
-															//var func = CKEDITOR.dialog.validate.integer( editor.lang.common.validateNumberFailed );
-															//var isValid = func.apply( this );
-															isValid = true;
-															if ( isValid )
+															var aMatch  =  this.getValue().match( regexValidSize );
+															if ( aMatch )
+															{
 																addChange( 'height', this, 'image' );
-															return isValid;
+																return true;
+															}
+															alert( editor.lang.common.validateNumberFailed );
+															return false;
 														}
 													}