I&#x27;m not sure I&#x27;d call QML a &quot;breakout success&quot;. There are definitely huge issues with it, notably:<p>* It&#x27;s quite incomplete. There are a <i>lot</i> of things you just can&#x27;t do in it. For example try doing a widget of the kind you&#x27;d use for compilation output in an IDE. There <i>is</i> a multiline text editor widget, but the only efficient operation is appending text - you can&#x27;t remove the first line for example.<p>* If you decide you will write your own QML widget (e.g. for the compilation output), you find that there is no way to render text! The scene graph text nodes are still private.<p>* You have to use Javascript (ugh)<p>* There&#x27;s quite a lot of friction converting C++ types to Javascript and vice versa. Especially with lists and arrays. For example when you access a C++ array from Javascript it has to copy the whole array into a native Javascript array, and then modifications are lost.<p>* The scope of files and IDs is quite messy - parents can refer to their children&#x27;s IDs, so there is no concept of data encapsulation. To be honest I still haven&#x27;t totally worked out the rules, but they&#x27;re a mess in any case.<p>* Dynamically creating dialogs and UI elements is a bit of a mess. The &quot;standard&quot; way to have dialogs is (more or less) to create all dialogs the program needs at startup and hide them all until needed. Obviously that doesn&#x27;t scale well for things like tooltips. Creating them dynamically is rather painful (especially when there are no examples for how to do it!)<p>QML is definitely a nice idea, but I think they need to give it a third try, and probably not use Javascript.