Hello everyone,
I am sending my Week 4 report (June 28 - July 2), you can also find it in the project wiki: https://trac.osgeo.org/grass/wiki/GSoC/2021/SingleWindowLayout#Week4.
1) What did I complete this week?
Similarly as the last week, I focused on the GUI refactoring. I worked on the main refactoring PR (see [1]). In terms of the main Map Display I am done here. However, me and my mentors realized that these changes influence also other Map Frames - particularly g.gui.rdigit, d.mon, Map Swipe, Ground Control Point and IClass frame.
There were two possible ways how to proceed. First, I started with the statusbars for all the frames that we need newly to be created based on wx.Statubar widget (see [2]). Then we came up with another concept, namely delegating methods using metaprogramming. Although this path seemed cheap at first (we talked about it very intensively on videocall on Wednesday), after a few hours of studying, we came to the conclusion that it is inappropriate in our case. And this decision subsequently opened PR [2] again.
Meantime, I also discovered the bug related to hiding statusbar and toolbars. Hiding does not work properly for above-mentioned map frames as e.g. Map Swipe. I set up the issue [3].
To sum it up, this week was not so productive in terms of code, but key in determining what to do next and especially how.
2) What am I going to achieve for next week?
In the next step, the focus will be on the completion of PR https://github.com/OSGeo/grass/pull/1689, which will then allow the completion of the large PR https://github.com/OSGeo/grass/pull/1675.
3) Is there any blocking issue?
No, it is not. However, as I have already mentioned I am on holiday from Saturday to Tuesday.
I am looking forward to new energy coming after the rest. 
[1] https://github.com/OSGeo/grass/pull/1675
[2] https://github.com/OSGeo/grass/pull/1689
[3] https://github.com/OSGeo/grass/issues/1691
Any suggestions are welcome.
Best wishes,
Linda Kladivova