Hello,
a. As for the background color, I wonder what actually is windows default. I checked my windows settings to be sure, and in adjustment-colors (or however it is called in other languages) I am using the "dark" option, and some blue as motive color, so the windows bottom layer is dark blue, the system settings window is black, file explorer is in shades of dark gray, whatever else recognizes this is also dark. And, new playroom client background is white. So, either there is something broken, or the "windows default" is actually set to "(ugly) white" no matter of the conditions.
b. In reading and appearance and colors, the options Use predefined colors for light/whitt background or the same for "dark/black" actually does totally nothing (only opens confirmation message and then the 2 already reported errors). I thought it would at least restore default settings, but I changed "Color 16: Blue 3" to actually be pink to test, and nothing happened. And what's more, selecting even "Restore default configuration" did not change a thing. I don't know if this is because of the portable version, but it seems to save the settings between sessions otherwise.
c. Note that the pure white background is actually difficult to look at, and may cause headache sooner or later (you could compare it to a high pitched voice reading your messages). Making at least light and dark version to choose from might be an option (and then I'd probably go for dark), yet since we can choose all the other colors of all the other items, it would be good to be able to choose the background color as well. I'd suggest making few default options to choose from, for example - light theme, dark theme, the website-like theme and an option to create your own. Maybe it was meant this way with the option described above, which doesn't work.
d. The website background color could be described as light blueish or greenish, maybe turquoise? I think the simplest way to describe it (especially for blinds) is by a RGB code, which must be somewhere in the website code, but I checked with some graphics program and it's "ddeeffff" in RGBA, standard, where A seems to be some transparency option (which is set at max anyways, so no transparency, omit the last 2 f for a 6 characters RGB code). It may seem a bit retro for some people, but I quite like it, and it's easy to look at.
e. As for the undesired message hiding, I actually figured out it could be changed from a table simply by opening settings by F10 (I am not really a hotkey person, I cannot seem to remember many hotkeys), which may work, but it is not very practical. But what I meant is basically hidden in reading and appearance - views. From what I heard, you can change the views by pressing alt + f1-fx (correct me if I am wrong) and filter for example only private messages, while in a table where the table discussion makes it difficult to keep in track of the private chat, but you don't want to leave the table for some reasons (you may want to read the table history later for example). I'd just like such an option accessible to sighted people as well. It may be a bit easier for a sighted person to orientate in a mess of different chats compared to blinds, given that the different types have different text color (which they do), but only to a certain extend. We are not superheroes.
f. I heard there are also some graphics changes in some games. I am actually curious about them, but at the same time not in a mood to play games right now. But I might get to it sooner or later, especially if the overal look of the client becomes satisfactory. :)
g. Edit: I just tested the "minimize to taskbar" function. It works, it's there, just it's pretty invisible - unlike other programs, that have a small icon, this appears only as an empty square that says "QuentinC Gameroom [username]" when I move my cursor over it.
Anyways thank you for your hard work and patience.