Call wxTheClipboard->UsePrimarySelection(true) when using wxClipboard, without getting into detail clipboard work very differently on X11. Without calling this copying to the clipboard won't work. I've just put it after every use of ->Open, this is safe as in every case Close() is called right after. This will fix clipboard copying on all unices.

Originally committed to SVN as r3431.

aegisub/src/dialog_colorpicker.cpp

@@ -1483,6 +1483,7 @@ void DialogColorPicker::OnRGBAdjust(wxCommandEvent &evt)
 	wxString data = wxString(_T("rgbadjust(")) + PrettyFloatD(r) + _T(",") + PrettyFloatD(g) + _T(",") + PrettyFloatD(b) + _T(")");
 
 	if (wxTheClipboard->Open())	{
+		wxTheClipboard->UsePrimarySelection(true);
 		wxTheClipboard->SetData(new wxTextDataObject(data));
 		wxTheClipboard->Close();
 	}

aegisub/src/dialog_style_manager.cpp

@@ -723,6 +723,7 @@ void DialogStyleManager::CopyToClipboard (wxListBox *list, std::vector<AssStyle*
 	}
 
 	if (wxTheClipboard->Open()) {
+		wxTheClipboard->UsePrimarySelection(true);
 		wxTheClipboard->SetData(new wxTextDataObject(data));
 		wxTheClipboard->Close();
 	}

aegisub/src/frame_main_events.cpp

@@ -438,6 +438,7 @@ void FrameMain::OnMenuOpen (wxMenuEvent &event) {
 		
 		bool can_paste = true;
 		if (wxTheClipboard->Open()) {
+			wxTheClipboard->UsePrimarySelection(true);
 			can_paste = wxTheClipboard->IsSupported(wxDF_TEXT);
 			wxTheClipboard->Close();
 		}

aegisub/src/subs_grid.cpp

@@ -976,6 +976,7 @@ void SubtitlesGrid::CopyLines(wxArrayInt target) {
 
 	// Send to clipboard
 	if (wxTheClipboard->Open()) {
+		wxTheClipboard->UsePrimarySelection(true);
 		wxTheClipboard->SetData(new wxTextDataObject(data));
 		wxTheClipboard->Close();
 	}

aegisub/src/timeedit_ctrl.cpp

@@ -388,6 +388,7 @@ void TimeEdit::CopyTime() {
 
 	// Time
 	if (wxTheClipboard->Open()) {
+		wxTheClipboard->UsePrimarySelection(true);
 		wxTheClipboard->SetData(new wxTextDataObject(GetStringSelection()));
 		wxTheClipboard->Close();
 	}

aegisub/src/video_display.cpp

@@ -682,6 +682,7 @@ void VideoDisplay::UpdateSubsRelativeTime() {
 ///
 void VideoDisplay::OnCopyToClipboard(wxCommandEvent &event) {
 	if (wxTheClipboard->Open()) {
+		wxTheClipboard->UsePrimarySelection(true);
 		wxTheClipboard->SetData(new wxBitmapDataObject(wxBitmap(VideoContext::Get()->GetFrame(-1).GetImage(),24)));
 		wxTheClipboard->Close();
 	}