Fix TinyMCE not launched and JS error in a Toggleable form if % sign used in width or height

Define a custom schema with 1 string field and 1 custom type implementing the custom schema.
In Listing&Views, Forms Layouts, define a form, include a "HTML text" widget type with properties "width" and "height" set to "100%" (HTML text to display the string field defined above).
In a new Tab (Listing&Views, Tabs), include a Toggleable form in the tab and associate the previous form in the "Layouts" field.
Activate the tab in a suitable way (Activation tab in Studio when defining the tab)
Deploy the application, create a document with HTML standard formatting of the custom type and invoke the form (in the tab).
The TinyMCE Editor will not launch in the Edit mode (what you see is then HTML source code instead of HTML formatted text) and pressing the "Modify" button will give a JS error, seen in the JavaScript console in the browser.

The issues occur due to the "%" sign.

If setting a value in dots instead of percentages (without "%" sign in "width" and "height" fields as done above), then the issues do not arise.