id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	blockedby	blocking	branch_state	votes
3571	High-level mouse API	mooffie	andrew_b	"We have about 20 widget classes and about 13 of them have mouse handlers.

== The problem ==

There are two problems with our mouse handlers:

- They are complicated to read (and write).

- They are buggy. First, they all respond to events initiated inside other widgets. Second, each has its own peculiar bugs.

== The cause ==

These two problems stem from the low-level nature of `Gpm_Event`, which is the structure around which our mouse handlers operate. This structure represents a mouse event occurring in the whole screen and is utterly oblivious to regions and to the concept of a region ""owning"" the mouse.

To see the problem, simply drag the mouse over the whole screen: the panel will respond, then the command line, then the history button, then the buttons bar. A snafu. If you release the mouse over a WButton, the WButton will always execute its command --even if you didn't initiate the mouse press inside this WButton.

Our mouse handlers are complex mainly because they try to work around this problem.

== A solution ==

This simple patch solves this issue by introducing a higher level mouse API (or should I say protocol). Mouse handlers then become simpler (examples follow). The existing old-style handlers can still be used.

The patch introduces `lib/widget/mouse.c` and `lib/widget/mouse.h`. There is **very little code** here: the reason for new files is just to keep things tidy.

== ""But why bother?"" ==

You may ask, ""why bother? who's using mouse in console anyway?!"". Well, this proposal makes the handlers simpler, often shorter, so it makes our code more maintainable.
"	task	closed	major	4.8.17	mc-core	master	fixed				3559	merged	committed-master