diff --git a/src/vs/platform/theme/common/tokenClassificationRegistry.ts b/src/vs/platform/theme/common/tokenClassificationRegistry.ts
index 882d5c7e3ab..2ecc4b0b023 100644
--- a/src/vs/platform/theme/common/tokenClassificationRegistry.ts
+++ b/src/vs/platform/theme/common/tokenClassificationRegistry.ts
@@ -26,6 +26,11 @@ export interface TokenClassification {
 	modifiers: number;
 }
 
+export interface TokenSelector {
+	match(classification: TokenClassification): number;
+	asString(): string;
+}
+
 export interface TokenTypeOrModifierContribution {
 	readonly num: number;
 	readonly id: string;
@@ -96,15 +101,13 @@ export interface TokenStyleDefaults {
 }
 
 export interface TokenStylingDefaultRule {
-	match(classification: TokenClassification): number;
-	selector: TokenClassification;
+	selector: TokenSelector;
 	defaults: TokenStyleDefaults;
 }
 
 export interface TokenStylingRule {
-	match(classification: TokenClassification): number;
-	value: TokenStyle;
-	selector: TokenClassification;
+	style: TokenStyle;
+	selector: TokenSelector;
 }
 
 /**
@@ -124,33 +127,39 @@ export interface ITokenClassificationRegistry {
 	/**
 	 * Register a token type to the registry.
 	 * @param id The TokenType id as used in theme description files
-	 * @description the description
+	 * @param description the description
 	 */
 	registerTokenType(id: string, description: string): void;
 
 	/**
 	 * Register a token modifier to the registry.
 	 * @param id The TokenModifier id as used in theme description files
-	 * @description the description
+	 * @param description the description
 	 */
 	registerTokenModifier(id: string, description: string): void;
 
 	getTokenClassification(type: string, modifiers: string[]): TokenClassification | undefined;
 
-	getTokenStylingRule(classification: TokenClassification, value: TokenStyle): TokenStylingRule;
+	/**
+	 * Parses a token selector from a selector string.
+	 * @param selectorString selector string in the form (*|type)(.modifier)*
+	 * @returns the parsesd selector
+	 * @throws an error if the string is not a valid selector
+	 */
+	parseTokenSelector(selectorString: string): TokenSelector;
 
 	/**
 	 * Register a TokenStyle default to the registry.
 	 * @param selector The rule selector
 	 * @param defaults The default values
 	 */
-	registerTokenStyleDefault(selector: TokenClassification, defaults: TokenStyleDefaults): void;
+	registerTokenStyleDefault(selector: TokenSelector, defaults: TokenStyleDefaults): void;
 
 	/**
 	 * Deregister a TokenStyle default to the registry.
 	 * @param selector The rule selector
 	 */
-	deregisterTokenStyleDefault(selector: TokenClassification): void;
+	deregisterTokenStyleDefault(selector: TokenSelector): void;
 
 	/**
 	 * Deregister a TokenType from the registry.
@@ -277,35 +286,40 @@ class TokenClassificationRegistry implements ITokenClassificationRegistry {
 	}
 
 
-	private newMatcher(selector: TokenClassification) {
-		const score = getTokenStylingScore(selector);
-		return (classification: TokenClassification) => {
-			const selectorType = selector.type;
-			if (selectorType !== TOKEN_TYPE_WILDCARD_NUM && selectorType !== classification.type) {
-				return -1;
-			}
-			const selectorModifier = selector.modifiers;
-			if ((classification.modifiers & selectorModifier) !== selectorModifier) {
-				return -1;
-			}
-			return score;
-		};
-	}
+	public parseTokenSelector(selectorString: string): TokenSelector {
+		const [type, ...modifiers] = selectorString.split('.');
+
+		const selectorClassification = this.getTokenClassification(type, modifiers);
+		if (!selectorClassification) {
+			return {
+				match: () => -1,
+				asString: () => selectorString
+			};
+		}
+		const score = getTokenStylingScore(selectorClassification);
 
-	public getTokenStylingRule(selector: TokenClassification, value: TokenStyle): TokenStylingRule {
 		return {
-			match: this.newMatcher(selector),
-			value,
-			selector
+			match: (classification: TokenClassification) => {
+				if (selectorClassification.type !== TOKEN_TYPE_WILDCARD_NUM && selectorClassification.type !== classification.type) {
+					return -1;
+				}
+				const selectorModifier = selectorClassification.modifiers;
+				if ((classification.modifiers & selectorModifier) !== selectorModifier) {
+					return -1;
+				}
+				return score;
+			},
+			asString: () => selectorString
 		};
 	}
 
-	public registerTokenStyleDefault(selector: TokenClassification, defaults: TokenStyleDefaults): void {
-		this.tokenStylingDefaultRules.push({ selector, match: this.newMatcher(selector), defaults });
+	public registerTokenStyleDefault(selector: TokenSelector, defaults: TokenStyleDefaults): void {
+		this.tokenStylingDefaultRules.push({ selector, defaults });
 	}
 
-	public deregisterTokenStyleDefault(classification: TokenClassification): void {
-		this.tokenStylingDefaultRules = this.tokenStylingDefaultRules.filter(r => !(r.selector.type === classification.type && r.selector.modifiers === classification.modifiers));
+	public deregisterTokenStyleDefault(selector: TokenSelector): void {
+		const selectorString = selector.asString();
+		this.tokenStylingDefaultRules = this.tokenStylingDefaultRules.filter(r => !(r.selector.asString() === selectorString));
 	}
 
 	public deregisterTokenType(id: string): void {
@@ -361,8 +375,12 @@ function registerDefaultClassifications(): void {
 		tokenClassificationRegistry.registerTokenType(id, description, deprecationMessage);
 
 		if (scopesToProbe || extendsTC) {
-			const classification = tokenClassificationRegistry.getTokenClassification(id, []);
-			tokenClassificationRegistry.registerTokenStyleDefault(classification!, { scopesToProbe, light: extendsTC, dark: extendsTC, hc: extendsTC });
+			try {
+				const selector = tokenClassificationRegistry.parseTokenSelector(id);
+				tokenClassificationRegistry.registerTokenStyleDefault(selector, { scopesToProbe, light: extendsTC, dark: extendsTC, hc: extendsTC });
+			} catch (e) {
+				console.log(e);
+			}
 		}
 		return id;
 	}
diff --git a/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts b/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts
index 6868714c914..a69ea27e832 100644
--- a/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts
+++ b/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts
@@ -27,7 +27,7 @@ import { ITextMateService, IGrammar, IToken, StackElement } from 'vs/workbench/s
 import { IWorkbenchThemeService } from 'vs/workbench/services/themes/common/workbenchThemeService';
 import { CancellationTokenSource } from 'vs/base/common/cancellation';
 import { ColorThemeData, TokenStyleDefinitions, TokenStyleDefinition } from 'vs/workbench/services/themes/common/colorThemeData';
-import { TokenStylingRule, TokenStyleData } from 'vs/platform/theme/common/tokenClassificationRegistry';
+import { TokenStylingRule, TokenStyleData, TokenStyle } from 'vs/platform/theme/common/tokenClassificationRegistry';
 import { IConfigurationService } from 'vs/platform/configuration/common/configuration';
 
 export interface IEditorSemanticHighlightingOptions {
@@ -546,9 +546,9 @@ class InspectEditorTokensWidget extends Disposable implements IContentWidget {
 		} else if (isTokenStylingRule(definition)) {
 			const scope = theme.getTokenStylingRuleScope(definition);
 			if (scope === 'setting') {
-				return `User settings`; // todo: print selector and style once selector is a string
+				return `User settings: ${definition.selector.asString()} - ${this._renderStyleProperty(definition.style, property)}`;
 			} else if (scope === 'theme') {
-				return `Color theme`; // todo: print selector and style once selector is a string
+				return `Color theme: ${definition.selector.asString()} - ${this._renderStyleProperty(definition.style, property)}`;
 			}
 			return '';
 		} else if (typeof definition === 'string') {
@@ -560,7 +560,14 @@ class InspectEditorTokensWidget extends Disposable implements IContentWidget {
 			}
 			return '';
 		} else {
-			return String(definition[property]);
+			return this._renderStyleProperty(definition, property);
+		}
+	}
+
+	private _renderStyleProperty(style: TokenStyle, property: keyof TokenStyleData) {
+		switch (property) {
+			case 'foreground': return style.foreground ? Color.Format.CSS.formatHexA(style.foreground, true) : '';
+			default: return style[property] !== undefined ? String(style[property]) : '';
 		}
 	}
 
diff --git a/src/vs/workbench/services/themes/common/colorThemeData.ts b/src/vs/workbench/services/themes/common/colorThemeData.ts
index 225a3ed565f..b781d3dd8d8 100644
--- a/src/vs/workbench/services/themes/common/colorThemeData.ts
+++ b/src/vs/workbench/services/themes/common/colorThemeData.ts
@@ -158,7 +158,7 @@ export class ColorThemeData implements IColorTheme {
 		}
 		if (this.tokenStylingRules === undefined) {
 			for (const rule of tokenClassificationRegistry.getTokenStylingDefaultRules()) {
-				const matchScore = rule.match(classification);
+				const matchScore = rule.selector.match(classification);
 				if (matchScore >= 0) {
 					let style: TokenStyle | undefined;
 					if (rule.defaults.scopesToProbe) {
@@ -178,16 +178,16 @@ export class ColorThemeData implements IColorTheme {
 			}
 		} else {
 			for (const rule of this.tokenStylingRules) {
-				const matchScore = rule.match(classification);
+				const matchScore = rule.selector.match(classification);
 				if (matchScore >= 0) {
-					_processStyle(matchScore, rule.value, rule);
+					_processStyle(matchScore, rule.style, rule);
 				}
 			}
 		}
 		for (const rule of this.customTokenStylingRules) {
-			const matchScore = rule.match(classification);
+			const matchScore = rule.selector.match(classification);
 			if (matchScore >= 0) {
-				_processStyle(matchScore, rule.value, rule);
+				_processStyle(matchScore, rule.style, rule);
 			}
 		}
 		return TokenStyle.fromData(result);
@@ -222,7 +222,7 @@ export class ColorThemeData implements IColorTheme {
 			});
 
 			if (this.tokenStylingRules) {
-				this.tokenStylingRules.forEach(r => index.add(r.value.foreground));
+				this.tokenStylingRules.forEach(r => index.add(r.style.foreground));
 			} else {
 				tokenClassificationRegistry.getTokenStylingDefaultRules().forEach(r => {
 					const defaultColor = r.defaults[this.type];
@@ -231,7 +231,7 @@ export class ColorThemeData implements IColorTheme {
 					}
 				});
 			}
-			this.customTokenStylingRules.forEach(r => index.add(r.value.foreground));
+			this.customTokenStylingRules.forEach(r => index.add(r.style.foreground));
 
 			this.tokenColorIndex = index;
 		}
@@ -704,9 +704,8 @@ function getScopeMatcher(rule: ITextMateThemingRule): Matcher<ProbeScope> {
 function readCustomTokenStyleRules(tokenStylingRuleSection: IExperimentalTokenStyleCustomizations, result: TokenStylingRule[] = []) {
 	for (let key in tokenStylingRuleSection) {
 		if (key[0] !== '[') {
-			const [type, ...modifiers] = key.split('.');
-			const classification = tokenClassificationRegistry.getTokenClassification(type, modifiers);
-			if (classification) {
+			try {
+				const selector = tokenClassificationRegistry.parseTokenSelector(key);
 				const settings = tokenStylingRuleSection[key];
 				let style: TokenStyle | undefined;
 				if (typeof settings === 'string') {
@@ -715,8 +714,10 @@ function readCustomTokenStyleRules(tokenStylingRuleSection: IExperimentalTokenSt
 					style = TokenStyle.fromSettings(settings.foreground, settings.fontStyle);
 				}
 				if (style) {
-					result.push(tokenClassificationRegistry.getTokenStylingRule(classification, style));
+					result.push({ selector, style });
 				}
+			} catch (e) {
+				// invalid selector, ignore
 			}
 		}
 	}
diff --git a/src/vs/workbench/services/themes/common/tokenClassificationExtensionPoint.ts b/src/vs/workbench/services/themes/common/tokenClassificationExtensionPoint.ts
index d0b63fc59e9..127177d52cf 100644
--- a/src/vs/workbench/services/themes/common/tokenClassificationExtensionPoint.ts
+++ b/src/vs/workbench/services/themes/common/tokenClassificationExtensionPoint.ts
@@ -237,20 +237,23 @@ export class TokenClassificationExtensionPoints {
 					tokenStyleDefault.dark = validateStyle(contribution.dark, 'semanticTokenStyleDefaults.dark', collector);
 					tokenStyleDefault.hc = validateStyle(contribution.highContrast, 'semanticTokenStyleDefaults.highContrast', collector);
 
-					const [type, ...modifiers] = contribution.selector.split('.');
-					const classification = tokenClassificationRegistry.getTokenClassification(type, modifiers);
-					if (classification) {
-						tokenClassificationRegistry.registerTokenStyleDefault(classification, tokenStyleDefault);
+					try {
+						const selector = tokenClassificationRegistry.parseTokenSelector(contribution.selector);
+						tokenClassificationRegistry.registerTokenStyleDefault(selector, tokenStyleDefault);
+					} catch (e) {
+						collector.error(nls.localize('invalid.selector.parsing', "configuration.semanticTokenStyleDefaults.selector': Problems parsing {0}.", contribution.selector));
+						// invalid selector, ignore
 					}
 				}
 			}
 			for (const extension of delta.removed) {
 				const extensionValue = <ITokenStyleDefaultExtensionPoint[]>extension.value;
 				for (const contribution of extensionValue) {
-					const [type, ...modifiers] = contribution.selector.split('.');
-					const classification = tokenClassificationRegistry.getTokenClassification(type, modifiers);
-					if (classification) {
-						tokenClassificationRegistry.deregisterTokenStyleDefault(classification);
+					try {
+						const selector = tokenClassificationRegistry.parseTokenSelector(contribution.selector);
+						tokenClassificationRegistry.deregisterTokenStyleDefault(selector);
+					} catch (e) {
+						// invalid selector, ignore
 					}
 				}
 			}