PageUp/Down not work if in search mode

[metasong]

convenient to find file/folder in gap-anywhere searching mode.

reproduce: type some chars in gap-anywhere mode in a large dir, then pageup/down

[mgunyho]

I have thought about this a bit, and I agree that PageUp/Down should do something while searching. However, it's a bit tricky to figure out what that something should be.

Right now, the scroll position of the screen is closely tied to the cursor position. When you press PageUp/Down when not searching, the cursor just moves down by the height of the screen. But if you're searching, the cursor can (and should) only jump to items that match the search. So if you press PageDown, what should happen?

• If the cursor moves to the next item that is outside the screen, we might scroll the view by just one position (if the cursor was at the bottom of the screen and there is an item right below it), which is not what you would expect when you press PageDown.
• If the cursor moves down so that we have moved at least a screenful, we might miss some items completely, which is also a bit confusing.
• What else could the logic be?

I'm not saying that this is impossible, but it will require quite a bit of thinking to get right, and a lot of tests in addition to the existing ones (note how there is one test of the scrolling that doesn't actually pass), because there are lots of edge cases.