Concerning Selection methods, the following information is partially pertinent to all editing, but is most important to keep in mind when using Drag and Drop Editing.
Originally, there was the column oriented timeline drag selection which can be seen in 1 of 3 ways:
The selection priority works like this. When the highlighted vertical drag column is in use (1), it has the highest precedence and is used as the selection. When the column is a single line (2), then the fall back selection is the [ in/out ] marker region, if they are set. When they are not set, and the cursor is flashing, then the selection start=end and the selection is empty, but it does have a position on the timeline which can be used for editing. This is input for the vertical style cut/paste drag/drop editing.
More recently, in addition to the column oriented timeline drag selection, there is now group capabilities which have various edit selections. These are created in the Drag and Drop editing mode by clicking edits to toggle select/deselection. These groups are input to a different (more modern) set of cut, paste and overwrite drag/drop editing. You can see this set of operations when you click on an edit with the middle mouse button, and are also available using the shortcuts shown. They are more like text editor commands to include ctrl+x=cut, ctrl+c=copy, ctrl+v=paste, and so on ...The keyboard Delete key is not hooked to these operations, and is hooked to the original editing methods.
In this group mode, if there are In/Out markers set, they enter the selection priority queue between the column selection and the cursor only. You can see the In/Out markers selected region colored line across the timebar (slightly underneath where the time, samples or frames show ) on the main timeline extending between the [ and ]. This means that when the highlighted cursor selection is empty, the In/Out selection will be used.
Summarizing: to select multiple edits/clips on the timeline you can simply use LMB on each edit. Or, if in Settings → Preferences → appearence tab → Flags we have enabled Clears before toggle, use CTRL + LMB on each edit.
There is also a faster way:
And there is a Drag mouse way (this requires that the cursor be on the first clip and from there you start the drag):
If using certain operating systems (for example Ubuntu and Arch) that might field the Alt key before it gets to CINELERRA-GG, you can use the following for both Select and Deselect instead:
The CINELERRA-GG Community, 2021