Add ability to customise the CSS and JS in ZMI via Properties.

Requested by customer who uses TTW approach.

docs/ZMI.rst

@@ -76,3 +76,23 @@ Example taken from `cmf.zmiicons`_:
 
 
 .. _`cmf.zmiicons` : https://github.com/zopefoundation/cmf.zmiicons
+
+
+Use custom resources via ZMI
+++++++++++++++++++++++++++++
+
+To add custom CSS or JavaScript resources via ZMI you have to add a property:
+
+* ``zmi_additional_css_paths`` for additional CSS
+* ``zmi_additional_css_paths`` for additional JavaScript
+
+The properties can have one of the following types:
+
+* ``string``
+* ``ustring``
+* ``lines``
+* ``ulines``
+
+The value of the properties have to be paths or URLs to CSS resp. JavaScript
+which will be included in the HTML of the ZMI. (Paths have to be resolvable by
+the browser aka not simple file system paths.)

src/App/Management.py

@@ -26,6 +26,7 @@
 from zExceptions import Redirect
 from zope.interface import implementer
 import itertools
+import six
 import zope.event
 
 try:
@@ -163,9 +164,11 @@ class Navigation(Base):
     def manage_page_header(self, *args, **kw):
         """manage_page_header."""
         kw['css_urls'] = itertools.chain(
-            *zope.component.subscribers((self,), ICSSPaths))
+            itertools.chain(*zope.component.subscribers((self,), ICSSPaths)),
+            self._get_zmi_additionals('zmi_additional_css_paths'))
         kw['js_urls'] = itertools.chain(
-            *zope.component.subscribers((self,), IJSPaths))
+            itertools.chain(*zope.component.subscribers((self,), IJSPaths)),
+            self._get_zmi_additionals('zmi_additional_js_paths'))
         return self._manage_page_header(*args, **kw)
 
     security.declarePublic('manage_zmi_logout')
@@ -188,6 +191,13 @@ def manage_zmi_logout(self, REQUEST, RESPONSE):
 </html>""")
         return
 
+    def _get_zmi_additionals(self, attrib):
+        # Get additional assets for styling ZMI defined on properties in ZMI.
+        additionals = getattr(self, attrib, ()) or ()
+        if isinstance(additionals, six.string_types):
+            additionals = (additionals, )
+        return additionals
+
 # Navigation doesn't have an inherited __class_init__ so doesn't get
 # initialized automatically.
 

src/App/tests/testManagement.py

@@ -1,11 +1,43 @@
-import unittest
+import Testing.ZopeTestCase
 
 
-class TestNavigation(unittest.TestCase):
+class TestNavigation(Testing.ZopeTestCase.ZopeTestCase):
 
     def test_interfaces(self):
         from App.interfaces import INavigation
         from App.Management import Navigation
         from zope.interface.verify import verifyClass
 
         verifyClass(INavigation, Navigation)
+
+    def test_Management__Navigation__manage_page_header__1(self):
+        """It respects `zmi_additional_css_paths` string property."""
+        self.folder.manage_addProperty(
+            'zmi_additional_css_paths', '/foo/bar.css', 'string')
+        self.assertIn('href="/foo/bar.css"', self.folder.manage_page_header())
+
+    def test_Management__Navigation__manage_page_header__2(self):
+        """It respects `zmi_additional_css_paths` ustring property."""
+        self.folder.manage_addProperty(
+            'zmi_additional_css_paths', '/foo/bar.css', 'ustring')
+        self.assertIn('href="/foo/bar.css"', self.folder.manage_page_header())
+
+    def test_Management__Navigation__manage_page_header__3(self):
+        """It respects `zmi_additional_css_paths` lines property."""
+        self.folder.manage_addProperty(
+            'zmi_additional_css_paths', ['/foo/bar.css', '/baz.css'], 'lines')
+        self.assertIn('href="/foo/bar.css"', self.folder.manage_page_header())
+        self.assertIn('href="/baz.css"', self.folder.manage_page_header())
+
+    def test_Management__Navigation__manage_page_header__4(self):
+        """It respects `zmi_additional_css_paths` ulines property."""
+        self.folder.manage_addProperty(
+            'zmi_additional_css_paths', ['/foo/bar.css', '/baz.css'], 'lines')
+        self.assertIn('href="/foo/bar.css"', self.folder.manage_page_header())
+        self.assertIn('href="/baz.css"', self.folder.manage_page_header())
+
+    def test_Management__Navigation__manage_page_header__5(self):
+        """It ignores an empty `zmi_additional_css_paths` property."""
+        self.folder.manage_addProperty(
+            'zmi_additional_css_paths', '', 'string')
+        self.assertNotIn('href=""', self.folder.manage_page_header())