My dock is positioned on the right. As I launch/quit/minimize applications, the width of the dock is always changing. This behavior either makes the dock overlap my maximized windows (maximized via Divvy), or it leaves a gap between right side of a window and the dock.
Is there a way to lock the size of the Dock so that it doesn't change regardless of the number of icons on it?
In a word, "No".
The dock is dynamically sized as you have found on the basis of the number of applications stored, or running, and the amount of document windows you may have minimised.
There is no way to stop it exhibiting this behaviour, and if you think about it it would cause considerable usability issues if it were to do so, as the only way to maintain a static width would be dynamic resizing of App/Document icons, which would eventually be too small to usefully identify.
If you don't like the overlap, then you can try a couple of workarounds:
If you want to lock the dock so that you can't resize it, run this command in a terminal:
defaults write com.apple.dock size-immutable -bool yes && killall Dock
If you want to unlock the dock so that you can resize it, run this command in a terminal:
defaults write com.apple.dock size-immutable -bool no && killall Dock
I would recommend setting your dock to minimise program window to their app icon. To do this go into your docks settings and click the option that states "minimise to dock icon"
This should prevent the dock from growing better or smaller. However the more programs you run the dock will increase in size. I suggest pinning the programs to the dock that you use most often and then resize your windows.
