Go to next change / Go to previous change should start from current cursor position

[Mingun]

Currently those actions starts from the first/last change if change is not selected (displayed as -/XX in diff dialog) or last selected change.

Common use case during refactoring: make many semi-related changes while refactor and then make several commits by select changes to commit from diff view. Each time when you stash particular change, the current change position is reset and you have to go thought all unrelated changes for current commit.

Assumed workflow:

• go from the first hunk to the last in the diff
• stage some hunk
• click to some place in the diff
• click to the Go to next change to move to the not yet processed hunk
  • currently: you go to the very first unstaged hunk

[goran-w]

@love-linger While this makes sense for the (default) chunk-navigation mode, could we PLEASE make this AutoUpdate() behavior optional for the BlockNavigation mode? (Because this is not how I intended BlockNavigation to work when I initially added it, and it is also not how most other Diff tools with similar block-stepping functionality are working!)

To explain: When I step through a diff (block by block) I sometimes scroll up/down to check context, but I still want to RETAIN the block-index I had stepped to. I.e. if I've currently stepped to block 5/8, I DON'T want that block-index (and the corresponding block-highlight) to jump around just because I'm scrolling...

To be clear: I'm fine with the implementation made from this issue, but I REALLY need an option / Preference to turn it off, since that is not the workflow I prefer when using BlockNavigation!

BTW, another related request that I really want to see implemented (and which may become easier to fix after the refactoring made here) is the one from #1655 and #1684. (Also, #1680 is a slightly related request to all of these.)

[goran-w]

Related commit 065ec2a adds an option 'Update current block while scrolling in diff view (Block-Navigation)' (true by default) in Preferences - thank you, @love-linger!

[goran-w]

Related commit 8ac5896 (by @love-linger) reworks this feature quite a bit:

• Instead of auto-updating the current active block on text-view scrolling, it now only auto-updates when caret position is changed.
• The (brand new) Preference-option 'Update current block while scrolling ...' mentioned in my previous comment was removed (since the feature was changed).
• The "Enable Block-Navigation" toggle-button was removed, and BlockNavigation is now the only mode used.

[Mingun]

BTW, what is Block Navigation and how it differs from another mode?

[goran-w]

Block Navigation differs in the following way from the the earlier default navigation-mode :

• It adds a <current>/<total> index-counter for diff-blocks (i.e. indexed block of changes).
• It adds a subtle highlighting of the "current" diff-block.
• It adds buttons for jumping to the First / Last Difference (block).
• It changes the behavior of the Previous / Next Difference buttons, so they jump more strictly to the prev/next diff-block (while the earlier default navigation-mode instead was jumping to the prev/next diff-block that is not currently "in view").