Improvements for the selection tool

Hi guys, how are you? As I said in other threads, I have been using lmms lately and while I have used it, I have found some minimal errors. (apparently irrelevant) but that make it more difficult to use in lmms.

Some of these errors have the selection tools.

Here I mention the errors and improvements of the selection in general in all the editors

Song Editor

• Delete clips grouped with the selection tool by pressing "delete" in the song editor. (#3649)
• Select the desired parts of a clip, instead of selecting the entire clip.
• Free selection in the song editor.
• Inverted selection in the song editor.
• Select multiple tracks in the song editor with selection tool or by pressing "Ctrl".

Beat Bassline

• Selection tool in the bb editor.
• Free selection of notes in the bb editor.
• Inverted selection in bb editor.

Piano Roll

• Free selection on the piano roll.
• Inverse selection of notes on the piano roll.
• Multiple selection of midi notes by pressing "Ctrl" inside the piano roll.

Automation editor

• Selection tool in the automation editor.
• Free selection of automation points.
• Inverted selection in the automation editor
• Multiple selection of automation points by pressing "Ctrl".

Sample Track

• Select the desired wave parts of the sample track.
• Select free in the wave of the sample track.
• Select inverted in the wave of the sample track.

Mixer FX

• Selection tool within the fx mixer.
• Select multiple channels by pressing "Ctrl".
• Select multiples in the effects window by pressing "Ctrl".
• Free selection in the channels and effects.

File Browser

• Multiple file selection by pressing "Ctrl".
• Selection tool in the file browser.

So far are the problems I've seen both the selection tool and the selection in general, maybe they are minimal errors, but they are very annoying and waste time. it does not always work by pressing "Ctrl". Greetings.

Start by reviewing the selection behavior in the Song Editor, Beat/Bassline, Piano Roll, Automation Editor, Sample Track, Mixer FX, and File Browser listed in the issue. Confirm with maintainers which selection improvement is in scope before beginning. Done means the agreed selection operations work consistently in that editor and are verified manually.