doc: update roadmap and further goals

README.md

@@ -106,25 +106,33 @@ the primary use-case for myself to create this library in the first place.
           - [ ] vertical
           - [ ] horizontal
       - [ ] Content alignment (i.e. standard calculations done with the provided `Size`)
-      - [ ] Text display
       - [x] User input
         - [x] single line
         - [x] multi line
       - [x] min size (provide size to use which would be a minimal size - as if the actual size is smaller then the `Container` will scroll and otherwise the contents expand to the available space instead?)
-      - [ ] image support through kitty protocol
+      - [ ] image support through kitty protocol (**later**)
+  - [ ] Inline rendering (**later**)
 - [ ] Examples
-  - [ ] scrollable content (i.e. show long text of an except of something and other smaller `Container`)
-    - [ ] min size
-    - [ ] mouse scrolling aware of mouse position
-  - [ ] layout options with different ways to create specific layouts
+  - [ ] Layouts
     - [ ] vertical
     - [ ] horizontal
     - [ ] grid
-    - [ ] mixed
+    - [ ] mixed (some sort of form)
   - [ ] Elements
-    - [ ] User input handling
-    - [ ] Text Input field
     - [ ] Button
+    - [ ] Text Input field
+    - [ ] User input handling
+    - [ ] Popup-menu
+    - [ ] Scrollable Content (i.e. show long text of an except of something and other smaller `Container`)
+      - [ ] min size
+      - [ ] mouse scrolling aware of mouse position (i.e. through multiple different scrollable `Container`)
+    - [ ] Launch sub-applications (not inside of a `Container` but during the application workflow, like an editor)
+  - [ ] Styles
+    - [ ] Text styles
+    - [ ] Color palette
+- [ ] Testability
+  - [ ] snapshot ability to safe current screen (from `Renderer`) to test against
+  - [ ] try to integrate them into the library itself such that they also serve as examples on how to test
 
 Decorations should respect the layout and the viewport accordingly. This means
 that scrollbars are always visible (except there is no need to have a scrollbar)
@@ -193,6 +201,10 @@ Afterwards this README file contents can be updated to provide an actual
 overview of the library in a short form containing links to the detailed
 information required for usage.
 
+The documentation may contain tips about how to implement corresponding event
+loops or how to design own `Element`s. And also on how to test accordingly and
+use the library itself for examples on how to design the test cases.
+
 ### Archive
 
 The alignment and sizing options only make sense if both are available. For