fixes #20688

src/vs/workbench/parts/debug/browser/debugEditorModelManager.ts

@@ -7,6 +7,7 @@ import * as nls from 'vs/nls';
 import { TPromise } from 'vs/base/common/winjs.base';
 import * as objects from 'vs/base/common/objects';
 import * as lifecycle from 'vs/base/common/lifecycle';
+import { Constants } from 'vs/editor/common/core/uint';
 import { Range } from 'vs/editor/common/core/range';
 import { IModel, TrackedRangeStickiness, IModelDeltaDecoration, IModelDecorationsChangedEvent, IModelDecorationOptions } from 'vs/editor/common/editorCommon';
 import { IWorkbenchContribution } from 'vs/workbench/common/contributions';
@@ -115,7 +116,7 @@ export class DebugEditorModelManager implements IWorkbenchContribution {
 		}
 
 		// only show decorations for the currently focussed thread.
-		const wholeLineRange = new Range(stackFrame.lineNumber, stackFrame.column, stackFrame.lineNumber, Number.MAX_VALUE);
+		const wholeLineRange = new Range(stackFrame.lineNumber, stackFrame.column, stackFrame.lineNumber, Constants.MAX_SAFE_SMALL_INTEGER);
 		const range = new Range(stackFrame.lineNumber, stackFrame.column, stackFrame.lineNumber, stackFrame.column + 1);
 
 		// compute how to decorate the editor. Different decorations are used if this is a top stack frame, focussed stack frame,
@@ -239,7 +240,7 @@ export class DebugEditorModelManager implements IWorkbenchContribution {
 	private createBreakpointDecorations(breakpoints: IBreakpoint[]): IModelDeltaDecoration[] {
 		return breakpoints.map((breakpoint) => {
 			const range = breakpoint.column ? new Range(breakpoint.lineNumber, breakpoint.column, breakpoint.lineNumber, breakpoint.column + 1)
-				: new Range(breakpoint.lineNumber, 1, breakpoint.lineNumber, 1);
+				: new Range(breakpoint.lineNumber, 1, breakpoint.lineNumber, Constants.MAX_SAFE_SMALL_INTEGER); // Decoration has to have a width #20688
 			return {
 				options: this.getBreakpointDecorationOptions(breakpoint),
 				range