87
edits
Changes
Creating new document
= Overview =
Gecko can have many scrollable frames at one time. This documents the detail of mouse wheel scrolling processing in Gecko.
= Gecko honors mouse cursor position =
Basically, turning mouse wheel scrolls a scrollable view under mouse cursor. This behavior was designed in [https://bugzilla.mozilla.org/show_bug.cgi?id=97283 bug 97283].
Note that on Windows, most mouse drivers honors keyboard focus rather than mouse cursor position. However, Internet Explorer and other web browsers honor the cursor position too. So, it's not a problem, probably.
= Deciding a scrolling target from cursor position =
There can be two or more scrollable frames at a point (i.e., under mouse cursor). Gecko decides one scrolling target by following rules:
# Finds a frame under mouse cursor.
# Checks whether the frame is scrollable to the direction by user operation.
# If the frame is scrollable, Gecko scrolls the frame.
# Otherwise, repeats the steps with its ancestor frames.
There is a special case. If gecko finds a drop down frame of a select element, it stops going up the frame hierarchy.
= Mouse wheel transaction =
= DOM event vs. Scrolling =
= Issues =
Gecko can have many scrollable frames at one time. This documents the detail of mouse wheel scrolling processing in Gecko.
= Gecko honors mouse cursor position =
Basically, turning mouse wheel scrolls a scrollable view under mouse cursor. This behavior was designed in [https://bugzilla.mozilla.org/show_bug.cgi?id=97283 bug 97283].
Note that on Windows, most mouse drivers honors keyboard focus rather than mouse cursor position. However, Internet Explorer and other web browsers honor the cursor position too. So, it's not a problem, probably.
= Deciding a scrolling target from cursor position =
There can be two or more scrollable frames at a point (i.e., under mouse cursor). Gecko decides one scrolling target by following rules:
# Finds a frame under mouse cursor.
# Checks whether the frame is scrollable to the direction by user operation.
# If the frame is scrollable, Gecko scrolls the frame.
# Otherwise, repeats the steps with its ancestor frames.
There is a special case. If gecko finds a drop down frame of a select element, it stops going up the frame hierarchy.
= Mouse wheel transaction =
= DOM event vs. Scrolling =
= Issues =
