feat: add support for axis title opacity menu

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: passed
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: na
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: na
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: passed
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

Author: kgryte

lib/node_modules/@stdlib/plot/base/view/lib/browser/app/editor/config/axis.js

@@ -27,7 +27,9 @@ var resolveTextValue = require( './resolve_text_value.js' );
 
 // VARIABLES //
 
-var PROPS = [];
+var PROPS = [
+	'titleOpacity'
+];
 var TEXT_PROPS = [
 	'title'
 ];

lib/node_modules/@stdlib/plot/base/view/lib/browser/app/editor/menus/axis.js

@@ -60,19 +60,13 @@ function addMenu( parent, conf, name ) {
 
 	def = defaults.axis;
 
-	// FIXME: remove this once we have proper defaults
-	def = {
-		'title': {
-			'property': 'title',
-			'default': '',
-			'type': 'string'
-		}
-	};
 	controllers = {};
 	for ( i = 0; i < keys.length; i++ ) {
 		k = keys[ i ];
 		d = def[ k ];
-		if ( k === 'titleColor' ) {
+		if ( k === 'title' ) {
+			controller = folder.add( conf, k );
+		} else if ( k === 'titleColor' ) {
 			controller = folder.addColor( conf, k );
 		} else if ( k === 'titleFont' ) {
 			controller = folder.add( conf, k );
@@ -88,8 +82,10 @@ function addMenu( parent, conf, name ) {
 		} else if ( k === 'titleLineHeight' ) {
 			controller = folder.add( conf, k )
 				.min( d.min );
-		} else if ( k === 'title' ) {
-			controller = folder.add( conf, k );
+		} else if ( k === 'titleOpacity' ) {
+			controller = folder.add( conf, k )
+				.min( d.min )
+				.max( d.max );
 		} else {
 			console.log( 'Unrecognized property in editor configuration. Key: %s.', k );
 			continue;

lib/node_modules/@stdlib/plot/base/view/lib/browser/app/schema/transforms/axis.js

@@ -29,7 +29,8 @@ var signalName = require( './../../utils/signal_name.js' );
 // VARIABLES //
 
 var PROPS = [
-	'title'
+	'title',
+	'titleOpacity'
 ];