Mouse scroll wheel scrolls through shell history on newly opened widget

[apjanke]

When I fire up a new QTerminal or QTermWidget example program, the mouse scroll wheel scrolls back and forth through my shell command history, instead of scrolling the screen contents, until I get some more text on the screen.

Expected Behavior

Scroll wheel always scrolls through terminal scrollback buffer. If there's no offscreen scrollback, moving scroll wheel does nothing.

Current Behavior

In a new window, moving the scroll wheel causes the shell in the term widget to scroll back through its command history.

If I do an ls -l or something else to get several lines of content into the terminal buffer, then moving the scroll wheel switches to scrolling the screen contents through the terminal scrollback buffer.

Steps to Reproduce (for bugs)

1. Launch QTermWidget example program
2. Scroll mouse wheel upwards before you do anything else

Context

Doesn't break anything; it's just confusing.

System Information

• Distribution & Version: macOS 10.14.3
• Kernel: Darwin Kernel Version 18.2.0
• Qt Version: 5.12.1
• liblxqt Version: ???
• Package version: head of master (commit 9ee754a)