Index: /CKEditor/trunk/_source/plugins/image/dialogs/image.js
===================================================================
--- /CKEditor/trunk/_source/plugins/image/dialogs/image.js	(revision 6591)
+++ /CKEditor/trunk/_source/plugins/image/dialogs/image.js	(revision 6592)
@@ -639,5 +639,5 @@
 															{
 																var aMatch  =  this.getValue().match( regexGetSizeOrEmpty ),
-																	isValid = !!( aMatch && aMatch[ 1 ] != 0 );
+																	isValid = !!( aMatch && parseInt( aMatch[1], 10 ) != 0 );
 																if ( !isValid )
 																	alert( editor.lang.common.invalidWidth );
@@ -652,5 +652,5 @@
 																	if ( value )
 																		element.setStyle( 'width', CKEDITOR.tools.cssLength( value ) );
-																	else if ( !value && this.isChanged( ) )
+																	else if ( !value && this.isChanged() )
 																		element.removeStyle( 'width' );
 
@@ -688,8 +688,9 @@
 															validate : function()
 															{
-																var aMatch = this.getValue().match( regexGetSizeOrEmpty );
-																if ( !aMatch || aMatch[1] == 0 )
+																var aMatch = this.getValue().match( regexGetSizeOrEmpty ),
+																	isValid = !!( aMatch && parseInt( aMatch[1], 10 ) != 0 );
+																if ( !isValid )
 																	alert( editor.lang.common.invalidHeight );
-																return !!aMatch;
+																return isValid;
 															},
 															setup : setupDimension,