OS is Linux Mint 19.3 Cinnamon.
After resetting my taskbar to default setting, I am getting a weird behaviour and tried everything to fix it without success.
The "quick launch" part on the left now also contains icons for all windows currently in use. They didn't appear anymore in the central part as usual. I added manually an applet for them in the central part, but it turns out they are crammed to the right, as the "quick launch" part occupies alost all taskbar. I couldn't find where I could put things back to normal, especially resizing the "quick launch" part to a smaller portion of the taskbar. Even if I remove applets in them the size stays the same. I tried editing mode of the panel but couldn't do the resizing. Below is a picture of this behaviour.
After removing and adding back applets, the taskbar looks like this, ie the extra space is between start button and quick launch applet. I just need to find a way to remove this space.