src/vs/workbench/browser/parts/editor/tabsTitleControl.ts/TabsTitleControl/doRedrawTabDirty
class TabsTitleControl:	private doRedrawTabDirty(isGroupActive: boolean, isTabActive: boolean, editor: EditorInput, tabContainer: HTMLElement): boolean {
		let hasModifiedBorderColor = false;

		// Tab: dirty (unless saving)
		if (editor.isDirty() && !editor.isSaving()) {
			tabContainer.classList.add('dirty');

			// Highlight modified tabs with a border if configured
			if (this.accessor.partOptions.highlightModifiedTabs) {
				let modifiedBorderColor: string | null;
				if (isGroupActive && isTabActive) {
					modifiedBorderColor = this.getColor(TAB_ACTIVE_MODIFIED_BORDER);
				} else if (isGroupActive && !isTabActive) {
					modifiedBorderColor = this.getColor(TAB_INACTIVE_MODIFIED_BORDER);
				} else if (!isGroupActive && isTabActive) {
					modifiedBorderColor = this.getColor(TAB_UNFOCUSED_ACTIVE_MODIFIED_BORDER);
				} else {
					modifiedBorderColor = this.getColor(TAB_UNFOCUSED_INACTIVE_MODIFIED_BORDER);
				}

				if (modifiedBorderColor) {
					hasModifiedBorderColor = true;

					tabContainer.classList.add('dirty-border-top');
					tabContainer.style.setProperty('--tab-dirty-border-top-color', modifiedBorderColor);
				}
			} else {
				tabContainer.classList.remove('dirty-border-top');
				tabContainer.style.removeProperty('--tab-dirty-border-top-color');
			}
		}

		// Tab: not dirty
		else {
			tabContainer.classList.remove('dirty', 'dirty-border-top');
			tabContainer.style.removeProperty('--tab-dirty-border-top-color');
		}

		return hasModifiedBorderColor;
	}