src/vs/editor/contrib/find/findWidget.ts/FindWidget/_updateButtons
class FindWidget:	private _updateButtons(): void {
		this._findInput.setEnabled(this._isVisible);
		this._replaceInput.setEnabled(this._isVisible && this._isReplaceVisible);
		this._updateToggleSelectionFindButton();
		this._closeBtn.setEnabled(this._isVisible);

		let findInputIsNonEmpty = (this._state.searchString.length > 0);
		let matchesCount = this._state.matchesCount ? true : false;
		this._prevBtn.setEnabled(this._isVisible && findInputIsNonEmpty && matchesCount && this._state.canNavigateBack());
		this._nextBtn.setEnabled(this._isVisible && findInputIsNonEmpty && matchesCount && this._state.canNavigateForward());
		this._replaceBtn.setEnabled(this._isVisible && this._isReplaceVisible && findInputIsNonEmpty);
		this._replaceAllBtn.setEnabled(this._isVisible && this._isReplaceVisible && findInputIsNonEmpty);

		this._domNode.classList.toggle('replaceToggled', this._isReplaceVisible);
		this._toggleReplaceBtn.setExpanded(this._isReplaceVisible);

		let canReplace = !this._codeEditor.getOption(EditorOption.readOnly);
		this._toggleReplaceBtn.setEnabled(this._isVisible && canReplace);
	}