Use the editable string picker for item type flags in the item editor.

rsrc/schemas/readme.md

@@ -313,6 +313,7 @@ names are used when showing the Pick Sound dialog in various places. The require
 attribute specifies which sound it applies to.
 * `<event>` - (max unbounded) Gives a name to a major event flag. These names are shown (and editable) when showing the Pick Event dialog in various places. The required `id` attribute specifies which event.
 * `<item-class>` - (max unbounded) Gives a name to an item special class. These names are shown (and editable) when showing the Pick Item Class dialog in various places. The required `id` attribute specifies which class.
+* `<item-typeflag>` - (max unbounded) Gives a name to an item type flag. These names are shown (and editable) when showing the Pick Item Type Flag dialog in the item editor. The required `id` attribute specifies which flag.
 
 Terrain Types
 -------------

rsrc/schemas/scenario.xsd

@@ -382,6 +382,15 @@
 					</xs:simpleContent>
 				</xs:complexType>
 			</xs:element>
+			<xs:element name="item-typeflag" minOccurs="0" maxOccurs="unbounded">
+				<xs:complexType>
+					<xs:simpleContent>
+						<xs:extension base="xs:string">
+							<xs:attribute name="id" use="required" type="xs:integer"/>
+						</xs:extension>
+					</xs:simpleContent>
+				</xs:complexType>
+			</xs:element>
 		</xs:sequence>
 	</xs:complexType>
 	<xs:element name="scenario">