One-Hand mice merge without horizontal wheel

[lededev]

One-Handed Mouse Merge for Mice Without Horizontal Scroll

For users with mice that only have a vertical scroll wheel, you can still perform one-handed merge actions.

How to Use:

• Merge from right to left: Hold down the right mouse button and click the left mouse button, which means Alt+Left merge.
• Merge from left to right: Hold down the right mouse button and click the middle mouse button, which means Alt+Right merge.

To make the newly added code more maintainable and understandable, I refactored the MouseHook.cpp code, using a state matrix to comprehensively cover various situations.

[sdottaka]

Hmm... isn't this too complicated?
I tried this and found it to take some getting used to. Also, it can lead to unexpected merges, like merging to the right but failing and moving on to the next difference, then merging to the left by mistake when you try to go back.

If you want to merge with just your right hand, I recommend enabling merge mode.
Check the File → Merge Mode menu item and you can navigate and merge differences with just the cursor keys.
For now, I'm hesitant to merge this PR.

[lededev]

I believe some users will find this feature useful, so I developed it. For those who don’t need it, it shouldn’t cause any issues as this operation is not frequently used and unlikely to be triggered accidentally. After clicking the middle button, users still have ample time to decide whether to proceed with the merge and which direction to scroll.

[lededev]

The Microsoft PowerToys FancyZones module includes a feature similar to this:

• Move a Window: Hold the left mouse button, drag the window to a zone.
• Drop in a Zone:
  • Hold the Shift key to drop the window in the zone.
  • Alternatively, keep holding the left mouse button and click the right mouse button to change the state, equivalent to holding Shift.
• Merge Zones:
  • Click the middle mouse button while holding the left mouse button. This simulates holding the Ctrl key, allowing you to merge zones and drop the window into a larger area spanning multiple zones.

[lededev]

I use a Logitech G502 mouse, which has a very firm middle button that requires significant pressure to activate. If your mouse's middle button is more sensitive, it might accidentally trigger while scrolling. As an alternative, I can modify this operation to be triggered by the left button instead. If switched to the left button, users will need to move their finger away from the scroll wheel to change the state and then return to the scroll wheel position. This greatly reduces the chance of accidental activation, but also lowers efficiency.

[lededev]

@sdottaka I've simplified the operation: holding the right mouse button and clicking the left button is equivalent to Alt+Left, while holding the right mouse button and clicking the middle button is equivalent to Alt+Right.

This method can be more efficient doing "merge" than using the keyboard alone in certain scenarios. For instance, when dealing with multi-line diff blocks and needing to select small block of differences in the middle of long lines to merge to the other side, using the mouse is often faster than using the keyboard. Once the selection is made by mouse, you can simply hold the right mouse button and click the left or middle button to complete all the operations with only one hand, without needing to switch to the keyboard.

One additional note: When merging text blocks selected with the mouse, you need to hover the mouse over the selected text area before pressing the right button. Otherwise, pressing the right button will cancel the selection. This is a characteristic of the editor itself, not a bug, and can be considered a usage limitation.

[sdottaka]

Thank you for updating the PR.
It's easier than the previous one. However, I don't know why, and I don't know if it will reproduce in your environment, but when I press the left or middle mouse button while pressing the right mouse button in the folder comparison window, WinMerge seems to hang up.

Also, I think that having six different ways of operating one function is too much. Sorry, but I will reject this PR.

Also, when copying to the right with Alt + Shift + Wheel Down, an unexpected IME switch occurs if you release the Alt key first.
Regarding this, I am thinking of deleting Alt + Shift + Wheel Down/Wheel Up.