I have a field on a table which is a lookup of another table. Multiple selection is allowed.
The lookup source has quite a number of rows. When I want to select a value, I write the first letters of the value and the magic happens: a short selection list appears and I chose the first of the values that I need.
However, I cannot use “control + left mouse button” for multiple selection. I have to write the first letters, select one value, write again the first letters, select the second value and so on.
Testing this on a multi-select lookup, apparently you just need to hover with your mouse the option you want to add and then add it by using the space bar.
Using the space bar actually only selects the option if you haven’t started searching for options (i.e. you haven’t typed text to filter options).
If you have typed text to filter options, you can use the Up/Down arrows to navigate the list of options and press Enter to select the option. (Pressing Enter again will submit your updated selections.) Unfortunately, the act of selecting an option clears whatever text you have typed. I can forward your feedback to our designers