Starting from v0.38 ZeroBrane Studio includes experimental support for scope aware variable indicators. These indicators are added to mark local, global, masked, and masking variables and are calculated in real-time as the code is being written. Having this ability changes the way you write code, and does catch a lot of errors and 'wrong thinking' cases.
ZeroBrane Studio provides default indicators that can be updated; both the colors and the appearance can be changed as described in the documentation. For example,
styles.indicator.varmasked = nil will disable masked indicator.
In addition to providing real-time indicators, the IDE uses the same mechanism to provide "Go To Definition" and "Rename All Instances" options available from the popup menu in the editor. The items in the popup menu also show the number of instances detected and the line where the definition is found. "Go To Definition" item is enabled for local variables/functions, function parameters, and loop variables.
You can quickly select instances of a variable by doing
Ctrl/Cmd-DblClick on it. All instances get selected with the main one having slightly darker background and can be edited to update the name. In addition to that you can navigate selected instances using
Find Next/F3 and
Find Previous/Shift-F3; it will move the selection to the next/previous instance (and scroll the editor to make it visible).